AMR-35

The Automitrailleuse de Reconnaissance 35 (AMR 35) was a French light tank used in WWII. It was not intended to reconnoitre and report as the name suggests but was a light armoured combat vehicle without a radio.

Development

With his AMR 33 not yet being delivered to the French army, Louis Renault used two production vehicles to improve the type. In the middle of February 1934 he sent the first to the testing commission, refitted with a much more powerful engine. To his dismay the commission did not allow the whole production run to be converted to the new type; but a subsequent order of 92 for the second vehicle with its more reliable four-cylinder engine was made on 3 July 1934 . This was to have the name AMR 35. Also eight command tanks were to be produced, with a much larger superstructure but without a turret, which would be called AMR 35 ADF. Renault called these the Renault YS. At this time however it became clear that the AMR 33 was a very unreliable tank: the suspension units were simply too weak to withstand the forces caused by driving cross-country. A complete redesign of the suspension was ordered, also to be used for the new Renault R35. Two types were considered; the first had two bogies, like the R 35. This Renault ZB was rejected, but in March 1936 twelve were ordered by China and four a few months later by the Yuan province administration. These were only delivered in 1940. The other had only one bogie per side and was accepted. The Renault factory designation was Renault ZT. Due to these delays, the first AMR 35 was only delivered on 22 April 1936. Meanwhile the Citroën factory had tried to take over the order by developing the AMR Citroën P 103 which had a very novel hydraulic suspension, but this project was rejected. The AMR 35 was somewhat larger than the AMR 33, being 3.84 m long, 1.76 m wide and 1.88 m tall. It weighed 6.5 metric tons and could reach a speed of 60 km/h, making it the fastest French tank of its day. The side armour was increased from 8 to 10 mm. Its only weapon was a 7.5 mm Reibel machine gun.

Variants: AMR 35 à mitrailleuse 13,2 - ZT2 - ZT3 - ZT4

In 1936 two more orders followed. The first entailed 20 AMR 35's and five each of two new types: the Renault ZT2 and the Renault ZT3; the second 55 AMR 35's, again five each of the ZT2 and ZT3, and five Renault YS's. So there was to be a total of 167 AMR 35's, 10 ZT2's, 10 ZT3's and 13 YS's: together 200 vehicles. The Renault ZT2 was a tank with a larger rounded cast steel APX 5 turret equipped with a 25 mm gun. Only at the end of 1939 enough funds were made available to produce the turrets and finish the tanks. The Renault ZT3 was a tank destroyer with the same 25 mm gun in a superstructure on the hull. Both the ZT2 and ZT3 were intended to give the AMR units some antitank capacity. Another, less effective attempt to this end was the production of a turret fitted with a 13.2 mm machine gun, which could penetrate 20 mm steel at 500 m. It is not yet known how many vehicles were of this improved type. Also in 1936, 21 Renault ZT4s were ordered for the colonial troops to replace their obsolete Renault FT-17's. As these troops still used the Hotchkiss 7.92 mm machine gun as their standard weapon, they wanted a tank with the same; it was decided in the motherland however that it would be cheaper to install the old colonial FT-17 machine gun turrets on new hulls of the AMR 35, so the latter were to be produced only. As the colonies refused this solution, no vehicles were built until February 1940 (despite the order being enlarged to 56), when it proved to be too late to resolve the deadlock: even at the time of the capitulation not a single turret had been fitted on the 40 vehicles produced. On 1 January 1939 129 chassis had been built of all subtypes.
World War II
In the Battle of France 120 AMR 33's and 187 ZT's were available. These were used to equip three squadrons in the 1st and 2nd DLM, 60 tanks in each division; one squadron in four Cavalry Light Divisions, for a total of 80 and two squadrons in the GRDI of five DIM, for a total of 100: so 300 vehicles in all. The organic strength however was 240, as each platoon of four had one tank as a reserve vehicle. It is an indication of the poor reliability of the AMR's that in some units organic strength was lowered to three for each platoon. The ZT3's were used in 6 and 7 GRDI. Six Renault YS's were used as artillery observation vehicles fitted with advanced telemetric optics. During the battle the 13.2 mm gun proved to be incapable of defeating even the German Spaehpanzer, its bullets being deflected by their sloped armour. However most AMR's were lost due to mechanical trouble. The Germans used some AMR 35's as the Panzerspaehwagen ZT 702 (f). The Renault YS's were also taken into service. The ZT4's, being brand new, were fitted with the schwerer Granatwerfer 84 in an open superstructure to produce a self-propelled 81 mm mortar. Category:French tanks Category:World War II French tanks Category:Interwar armored fighting vehicles

Tank
: This article is about armoured fighting vehicles. For other meanings, see Tank (disambiguation). Tank (disambiguation) A tank is a tracked, armoured combat vehicle (armoured fighting vehicle), designed primarily to engage enemy forces by the use of direct fire. A modern main battle tank is distinguished by its high level of firepower, mobility and armour protection relative to other vehicles of its era. It can cross comparatively rough terrain at high speeds, but is fuel, maintenance, and ammunition-hungry and is logistically demanding. It has the heaviest armour of any vehicle on the battlefield, and carries a powerful weapon able to engage a wide variety of ground targets. It is among the most versatile and fearsome weapons on the battlefield, valued for its shock action against other troops and high survivability. Tank organisations (or armoured units) are usually employed with infantry in combined arms warfare, supported by engineers, artillery, aircraft, and other support arms. If not properly protected, tanks can be vulnerable to attack by infantry, mines, artillery, and aircraft strikes. Tanks were first used in the First World War, to break the deadlock of the trenches, and they evolved to take the role of cavalry on the battlefield. The name tank first arose in British factories making the hulls of the first battle tanks: the workmen were given the impression they were constructing tracked water containers for the British Army, hence keeping the production of a fighting vehicle secret. Tanks and tank tactics have undergone many generations of evolution over nearly a century. Although weapons systems and armour continue to be developed, many nations have been reconsidering the need for such heavy weaponry in a period characterised by unconventional warfare.
History
: Main article: History of the tank
World War One: the first tanks
Having already seen Rolls Royce armoured cars used by Royal Naval Air Service in 1914, and aware of schemes to create a tracked fighting vehicle, First Lord of the Admiralty Winston Churchill sponsored the Landships Committee to oversee development of this new weapon. The first successful prototype tank, nicknamed Little Willie, was tested for the British Army on September 6, 1915. Although initially termed landships by the Admiralty, the initial vehicles were colloquially referred to as water-carriers, later shortened to tanks, to preserve secrecy. The word tank was used to give the workers the impression they were constructing tracked water containers for the British army in Mesopotamia, and it was made official on December 24, 1915. 1915The first tank became operational when Captain H. W. Mortimore of the Royal Navy took a Mark I into action at Delville Wood during the Battle of the Somme on September 15 1916. The French developed the Schneider CA1 working from Holt caterpillar tractors, and first used it on April 16 1917. The first successful use of massed tanks in combat occurred at the Battle of Cambrai on November 20, 1917. The tank would eventually make trench warfare obsolete, and the thousands of tanks fielded during the war by French and British forces made a significant contribution. Initial results with tanks were mixed, with problems in reliability (and impatience high command) causing considerable attrition in combat. Deployment in small groups also lessened their tactical value and impact, which was at first formidable. German forces suffered from shock and lacked counter-weapons, though they did (accidentally) discover solid anti-tank shot, and used of wider trenches to limit the British tanks' mobility. This and unreliability forced Allied tanks to continue evolving for the duration of the war, including models such as the very long Mark V (which could navigate large obstacles, especially wide trenches, more easily than many modern AFVs), while Germany mostly fielded a small number of captured tanks, and only made twenty of their native design, the A7V. Demands from infantry to have tanks close by would have pernicious effects on British tank design and tactics well into WW2.
1920s to the end of Second World War
With the tank concept now established, several nations designed and built tanks between the two world wars. The British designs were the most advanced, due largely to their successes in WWI, to the state of the other European powers France and Germany, and the detachment of the USA. Throughout this period several classes of tanks were common, most of this development taking place in the UK. Light tanks, typically weighing ten tons or less, were used primarily for scouting and generally mounted a light gun that was useful only against other light tanks. The medium (or cruiser tanks as they were known in the UK) were somewhat heavier and focussed on long-range high-speed travel. Finally, the heavy or infantry tanks were heavily armoured and generally very slow. The overall idea was to use infantry tanks in close concert with infantry to effect a breakthrough, their heavy armour allowing them to survive with enemy antitank weapons. Once this combined force broke the enemy lines, groups of cruiser tanks would be sent through the gap, operating far behind the lines to attack supply lines and command units. This one-two punch was the basic combat philosophy of the British tank formations, and was adopted by the Germans as a major component of the blitzkrieg concept. J.F.C. Fuller's doctrine of WWI was the fount for work by all the main pioneers: Hobart in Britain, Guderian in Germany, Chaffee in the U.S., de Gaulle in France, and Tukhachevsky in the USSR. All came to roughly the same conclusions, Tukhachevsky's integration of airborne pathfinders arguably the most sophisticated; only Germany would actually put the theory to practise, and it was their superior tactics, not superior weapons, that made blitzkrieg so formidable. There was thought put into tank-against-tank combat, but the focus was on powerful antitank guns and similar weapons, including dedicated antitank vehicles. This achieved its fullest expression in the United States, where tanks were expected to avoid enemy armour, and let dedicated tank destroyer units deal with them. Britain took the same path, and both produced light tanks in the hope that with speed, they could avoid being hit, comparing tanks to ducks. In practice these concepts proved dangerous. As the numbers of tanks on the battlefield increased, the chance of meetings grew to the point where all had to be an effective antitank vehicle as well; moreover, tanks designed to cope only with other tanks were helpless against antitank guns. This led to a rapid up-armouring and up-gunning of almost all tank designs. Tank shape, previously guided purely by considerations of obstacle clearance, now became a trade-off, with a low profile desirable for stealth and stability. World War II saw a series of advances in tank design. Germany for example, initially fielded lightly armoured and lightly armed tanks, such as the Panzer I, which had been intended for training use only. These fast-moving tanks and other armoured vehicles were a critical element of the Blitzkrieg. However, they fared poorly in direct combat with British tanks and suffered severely against the Soviet T-34, which was superior in armour and weaponry. By the end of the war all forces had dramatically increased their tanks' firepower and armour; for instance, the Panzer I had only two machine guns, and the Panzer IV, the "heaviest" early war German design, carried a low-velocity 75mm gun and weighed under twenty tonnes. By the end of the war the standard German medium tank, the Panther, mounted a powerful, high-velocity 75mm gun and weighed forty-five tonnes. Another major wartime advance was the introduction of radically improved suspension systems. Although this might not sound important, the quality of the suspension is the primary determinant of a tank's cross-country performance. Tanks with limited suspension travel subject their crew to massive shaking, making operation difficult, limiting speed, and making firing on the move practically impossible. Newer systems like the Christie or torsion bar suspension dramatically improved performance, allowing the late-war Panther to travel cross country at speeds that would have been difficult for earlier designs to reach on pavement. By this time most tanks were equipped with radios (all U.S. and German, some Soviet; British radios were common, but often of indifferent quality), vastly improving the direction of units. Tank chassis were adapted to a wide range of military jobs, including mine-clearing and combat engineering tasks. All major combatant powers also developed specialised self-propelled guns: artillery, tank destroyers, and assault guns (armoured vehicles carrying large-calibre guns). German and Soviet assault guns, simpler and cheaper than tanks, had the heaviest guns in any vehicles of the war, while American and British tank destroyers were scarcely distinguishable (except in doctrine) from tanks. Turrets, which were not previously a universal feature on tanks, were recognised as the way forward. It was appreciated that if the tank's gun was to be used to engage armoured targets then it needed to be as large and powerful as possible, making having one large gun with an all-round field of fire vital. Multiple-turreted tank designs like the Soviet T-35 were abandoned by World War II. Most tanks retained at least one hull machine gun. Even post-war, the M60 MBT had a smaller secondary turret for the commander's cupola.
The Cold War and beyond
M60's Tiananmen Square during the 1989 protests
Jeff Widener (The Associated Press) ]] After WWII, tank development proceeded largely as it had before, with improvements to both the medium and heavy classes. Light tanks were now limited to the reconnaissance role, and in U.S. use, airborne support as well. However, the weight limitations of air transport made a practical light tank almost impossible to build, and this class gradually disappeared over time. But the seeds for a true transformation had already been working their way into existing designs. A combination of better suspensions and greatly improved engines allowed late-war medium tanks to outperform early-war heavies. With only slightly more armour and somewhat larger engines to compensate, mediums were suddenly protected against almost all antitank weapons, even those mounted on heavy tanks, while at the same time having the mobility of a medium tank. Many consider the turning point to be the Panther, which became the basis for almost every tank design after it. However the Panther was not terribly well armoured, and could not really fight the heavy tanks on an equal basis. 1989 protests]] The first tank to 'get it all right' is generally considered to be the British Centurion tank, which (in its later versions) was able to take hits from the infamous German 88 mm gun, was armed with the deadly 105 mm Royal Ordnance L7 that was superior to anything in the field, and could reach 56 km/h due to its excellent 650-hp Rolls-Royce Meteor engine. The Centurion replaced all British medium cruiser tanks and led to the demise of the heavy infantry tank class entirely, becoming what the British referred to as the Universal Tank, soon to be known as the main battle tank in most forces, abbreviated MBT. In response to the threat of heavy antitank guided missiles (ATGMs), the focus in development shifted away from just a tank's size, to the technologies within it. The long range of ATGMs made it useless to concentrate resources into fewer heavy tanks, because they could no longer perform in the stand-off role, the one thing they were really useful for. So rather than just producing tanks with much thicker armour, radically more effective armour was implemented. Gun technology remained remarkably similar even to WWI-era gun technology, with most tanks in service still being manually loaded, but with big advances in shell effectiveness. Although the basic roles and traits of tanks were almost all developed by the end of WWI, the performance of twenty-first-century counterparts had increased by an order of magnitude. They had been refined dramatically in response to continually changing threats and requirements, especially the threat of other tanks. The advancing capabilities of tanks have been balanced by developments of other tanks and by continuous development of antitank weapons.
Design
The three traditional factors determining a tank's effectiveness are its firepower, mobility and protection. The psychological effect on enemy soldiers of a tank's imposing battlefield presence is called shock action. Firepower is the ability of a tank to defeat a target. This takes into account the maximum distance at which targets can be engaged, the ability to engage moving targets, the speed with which multiple targets can be attacked, and the capability to defeat armoured vehicles or entrenched infantry. Mobility includes the speed and agility of driving cross-country, the types of terrain that can be covered, the dimensions of obstacles, trenches, and water that can be crossed, the ability to cross small bridges, and the distance that can be covered before refuelling is required. "Strategic mobility" also includes the ability to travel at high speed on roads, and the ability to be carried on rail or truck transport. Traditionally AFV mobility is measured by the following metrics:
- engine power
- engine torque
- power-to-weight ratio
- road speed
- off-road speed (a somewhat nebulous figure given the possible variation)
- road range
- off-road range
- weight (bridge classification)
- ground pressure
- width of trench crossed
- vertical step climbed
- angle of slope that can be climbed
- angle of side slope that can be negotiated
- ground clearance
- unprepared fording depth
- prepared fording depth (if different) Protection is the amount of armour, the type(s), how it is arranged (i.e., sloped or not), and which areas are given more protection (e.g., the turret and tracks) and which receive less (e.g., the rear of the chassis). It also includes low profile, low noise and thermal signature, active countermeasures and other methods of avoiding enemy fire, and the ability to continue fighting after damage has been sustained. Tank design is traditionally held to be a compromise between these three factors—it is not considered possible to maximise all three. For example, increasing protection by adding armour will increase weight and therefore decrease manoeuvrability; increasing firepower by using a larger gun will decrease both manoeuvrability and protection (due to decreased armour at the front of the turret). How the compromise is achieved is influenced by a combination of factors, including military strategies, budget, geography, political will, and the requirement to sell the tank to other countries. Examples of how different countries are influenced in their decisions are as follows:
- Britain has historically opted for better firepower and increased protection at the expense of some manoeuvrability. Britain maintains a small, highly trained professional army, and so tank crew survivability is important. As limited resources may be available, the crew needs to be able to maintain their tanks in the field.
- The USA has a large army with sophisticated weaponry and a complex array of mobile support services. As their tanks are expected to rarely be away from support and repair units, less emphasis is placed on the crew's ability to maintain the tank themselves or to continue fighting with it once damage has been sustained.
- Germany's tanks were completely outmatched by the Soviet T-34 on the WWII Eastern front. It lost more of its insufficiently-developed Tiger and Panther tanks due to mechanical breakdowns than enemy action. As a result, German tanks since have been designed to be very manoeuvrable, with a resulting decrease in protection. Enhanced reliability and lower maintenance requirements have also been important design goals.
- Soviet tanks are traditionally rugged, simple for production and maintenance ("quantity turns into quality"), as exemplified by the T-34. State-controlled design development proceeds in incremental changes. Extensive maintenance is expected to be done in specialized depots.
- Israel is a small, but relatively rich, nation, with limited manpower in a hostile political environment. Its primary concern is therefore crew survivability. To this end it is the only nation to have produced a main battle tank with the engine placed at the front and fuel surrounding the crew, to increase protection.
Weapons
Israel.]] The main weapon of any modern tank is a single large gun. Tank guns are among the largest-calibre weapons in use on land, with only a few artillery pieces being larger. Although the calibre has not changed substantially since the end of the Second World War, modern guns are technologically superior. The current common sizes are 120mm calibre for Western tanks and 125mm for Eastern (Soviet and Chinese legacy) tanks. Tank guns have been able to fire many types of rounds, but their current use is commonly limited to kinetic energy (KE) penetrators and high explosive (HE) rounds. Some tanks can fire missiles through the gun. Smoothbore (rather than rifled) guns are the dominant type of gun today. The British Army and the Indian Army are now the only ones to field main battle tanks carrying rifled guns. Modern tank guns are generally fitted with thermal jackets which reduce the effect of uneven temperature on the barrel. For instance, if it were to rain on a tank barrel the top would cool faster than the bottom, or a breeze on the left might cause the left side to cool faster then the right. This uneven cooling will cause the barrel to bend slightly and will effect long range accuracy. Usually, tanks carry other armament for short range defence against infantry or targets where the use of the main weapon would be ineffective or wasteful. Typically, this is a small calibre (7.62 to 12.7 mm) machine gun mounted coaxially with the main gun. However, a couple of French tanks such as the AMX-30 and AMX-40 carry a coaxial 20mm cannon that has a high rate of fire and can destroy lightly armoured vehicles. Additionally, many tanks carry a roof-mounted or commander's cupola machine gun for close-in ground or limited air defence. The 12.7-mm and 14.5-mm machine guns commonly carried on US and Russian tanks and the French Leclerc are also capable of destroying lightly-armoured vehicles at close range. Some tanks have been adapted to specialised roles and have had unusual main armament such as flame-throwers. These specialised weapons are now usually mounted on the chassis of an armoured personnel carrier.
Fire control
flame-thrower, can fire with reasonable accuracy while moving.]] Historically, tank weapons were aimed through simple optical sights and laid onto target by hand, with windage estimated or assisted with a reticule. Range to the target was estimated with the aid of a reticule (markings in the gun sight which are aligned to frame an object of known size, i.e. a tank), which was later supplemented with a stereoscopic range-finder, later replaced by a laser range-finder. Consequently, accuracy was limited at long range and made concurrent movement and shooting largely impossible. Most modern main battle tanks in the armies of industrialised countries use a laser range-finder but optical and reticule range-finders are still in use in older and less sophisticated vehicles. Modern tanks have a variety of sophisticated systems to make them more accurate. Gyroscopes are used to stabilise the main weapon; computers calculate the appropriate elevation and aim-point, taking input from sensors for wind speed, air temperature, humidity, the gun-barrel temperature, warping and wear, the speed of the target (calculated by taking at least two sightings of the target with the range-finder), and the movement of the tank. Infrared, light-amplification, or thermal night vision equipment is also commonly incorporated. Laser target designators may also be used to illuminate targets for guided munitions. As a result modern tanks can fire reasonably accurately while moving.
Ammunition
There are several types of ammunition designed to defeat armour, including High explosive squash head (HESH, also called high explosive plastic, HEP), High explosive antitank (HEAT), and kinetic energy penetrators (KEP, or armour-piercing discarding sabot APDS). For accuracy, shells are spun by gun-barrel rifling, or fin-stabilized (APFSDS, HEAT-FS, etc.). Some tanks, including the M551 Sheridan, T-72, T-64, T-80, T-90, T-84, and PT-91 can fire ATGMs (anti-tank guided missile) through their gun barrel. This functionality extends the effective combat range of the tank beyond the range afforded by conventional shells. It also provides the tank with a useful weapon against slow, low-flying airborne targets like helicopters. The United States has abandoned this concept, phasing the M551 and M60A2 out of their forces in favour of helicopters and aircraft for long range anti-tank roles, but CIS countries continue to employ gun-missile systems in their main battle tanks.
Protection
CIS, 4th Tank Battalion, 4th Marine Division, US Marines.]] The main battle tank is the most heavily armoured vehicle in modern armies. Its armour is designed to protect the vehicle and crew against a wide variety of threats. Commonly, protection against kinetic energy penetrators fired by other tanks is considered the most important. Tanks are vulnerable to antitank guided missiles; antitank mines, larger bombs, and direct artillery hits can also disable or destroy a tank. Tanks are especially vulnerable to airborne threats. Most modern MBTs do offer near complete protection from artillery fragmentation and lighter antitank weapons such as rocket propelled grenades. The amount of armour needed to protect against all conceivable threats from all angles would be far too heavy to be practical, so when designing an MBT much effort goes into finding the right balance between protection and weight.
Armour
Most armoured fighting vehicles are manufactured of hardened steel plate, or in some cases aluminium. The relative effectiveness of armour is expressed by comparison to rolled homogeneous armour. Most armoured vehicles are best-protected at the front, and their crews always try to keep them pointed toward the likeliest direction of the enemy. The thickest and best-sloped armour is on the glacis plate and the turret front. The sides have less armour and the rear and roof are least protected. World War Two American M4 Medium (British name, Sherman) tank crews found the German Tigers to be practically invulnerable from the front, and were forced to employ flank attacks. Today, tanks are vulnerable to specialised top-attack missile weapons and air attack. During WW2, aircraft rockets earned a formidable reputation, especially in France after the Normandy landings (Operation Neptune); post-war analysis revealed many reported kills were near-misses. Aircraft cannon firing armour-piercing ammunition, such as the Hurribomber's 40mm or Stuka's 37mm, could be effective, also. Even a simple Molotov cocktail on the engine deck, however, may disable or destroy any tank. Before the Second World War, Soviet tank designers started to slope the armour on several tanks, most famously the T-34. Angling armour plates greatly increases their effectiveness against projectiles, by increasing the effective perpendicular thickness of the armour, and by increasing the chance of deflection. German tank crews were said to be horrified to find that shots fired at the angled plates of T-34s would sometimes simply ricochet. Even light infantry antitank weapons can immobilise a tank by damaging its suspension or track. Many tracked military vehicles have side skirts, protecting the suspension. High explosive antitank weapons (HEAT), such as the bazooka, were a new threat in the Second World War. These weapons carry a warhead with a shaped charge, which focuses the force of an explosion into a narrow penetrating stream. Thin plates of spaced armour, steel mesh "RPG screens", or rubber skirts, were found to cause HEAT rounds to detonate too far from the main armour, greatly reducing their penetrating power. Some antitank ammunition (HESH or HEP) uses flexible explosive material, which squashes against a vehicle's armour, and causes dangerous spalling of material inside the tank which may kill the crew without penetrating the armour. As a defence, some vehicles have a layer of anti-spall material lining their insides. Since the 1970s, tanks have been protected by more complex perforated or composite armour, a sandwich of various alloys and ceramics. One of the best types of passive armour is the British-developed Chobham armour, which is comprised of spaced ceramic blocks contained by a resin-fabric matrix between layers of conventional armour. A form of Chobham armour is encased in depleted uranium on the very well-protected M1A1 Abrams MBT. The Israeli Merkava tank takes the design of protection systems to an extreme, using the engine and fuel tanks as secondary armour.
Grenade launchers, smoke and passive defences
Most armoured vehicles carry smoke grenade launchers which can rapidly deploy a smoke screen to visually shield a withdrawal from an enemy ambush or attack. The smoke screen is very rarely used offensively, since attacking through it blocks the attacker's vision and gives the enemy an early indication of impending attack. Modern smoke grenades work in the infrared as well as visible spectrum of light. Some smoke grenades are designed to make a very dense cloud capable of blocking the laser beams of enemy target designators or range finders and of course obscuring vision, reducing probability of a hit from visually aimed weapons, especially low speed weapons, such as antitank missiles which require the operator to keep the tank in sight for a relatively long period of time. In many MBTs, such as the French-built Leclerc, the smoke grenade launchers are also meant to launch tear gas grenades and anti-personnel fragmentation grenades. Many Israeli tanks contain small vertical mortar tubes which can be operated from within the tank, enhancing the anti-personnel capabilities and allowing it to engage targets which are behind obstacles. There have been proposals to equip other tanks with dual-purpose smoke/fragmentation grenade launchers that can be reloaded from the interior. Prior to the widespread introduction of thermal imaging the most common smoke grenade in AFV launchers was white phosphorus which created a very rapid smoke screen as well as having a very useful incendiary effect against any infantry in the burst area (e.g., infantry attempting to close with hand placed charges or mines). Since the advent of thermal imagers most tanks carry a smoke grenade that contains a plastic or rubber compound whose tiny burning fragments provide better obscurant qualities against thermal imagers. Some tanks also have smoke generators which can generate smoke continuously, rather than the instantaneous, but short duration of smoke grenades. Generally smoke generators work by injecting fuel into the exhaust, which partially burns the fuel, but leaves sufficient unburned or partially burned particles to create a dense smoke screen. Modern tanks are increasingly being fitted with passive defensive systems such as laser warning devices, which activate an alarm if the tank is "painted" by a laser range-finder or designator. Other passive defences include radio warning devices, which provide warning if the tank is targeted by radar systems that are commonly used to guide antitank weapons such as a millimetre and other very short wave radar.
Countermeasures
Passive countermeasures, like the Russian Shtora system, attempt to jam the guidance systems of incoming guided missiles. Explosive reactive armour, or ERA, is another major type of protection against high explosive antitank weapons, in which sections of armour explode to dissipate the focussed explosive force of a shaped charge warhead. Reactive armour is attached to the outside of an MBT in small, replaceable bricks. Active protection systems go one step further than reactive armour. An APS uses radar or other sensing technology to automatically react to incoming projectiles. When the system detects hostile fire, it calculates a firing resolution and directs an explosive-launched counter-projectile to intercept or disrupt the incoming fire a few metres from the target.
Exposed crew
Paradoxically, a tank is usually in its safest state when the commander is in a personally unsafe position, riding in the open, head out of the turret, with no personal protection save his helmet and a flak jacket. In this rather high position the commander can see around the vehicle with no restrictions, and has the greatest chance of spotting enemy antitank operations or natural and unnatural obstacles which might immobilise or slow down the tank. Tank periscopes and other viewing devices give a sharply inferior field of vision and sense of the countryside, despite constant advances in optics and electronics. Thus, when a tank advances in hostile territory with hatches closed, the commander and the crew might be personally safer, but the tank as a whole is more at risk given the extremely reduced vision. Improvements in onboard optical systems are ongoing, in order to overcome this problem.
Mobility
periscopei Merkava Mk-III) allow it to tackle most types of terrain, but they are only lightly armoured and are prone to mechanical failure.]] There are essentially two main aspects of mobility to consider, the tank's basic mobility such as its speed across terrain and ability to climb obstacles, and its overall battlefield mobility such as range, what bridges it can cross, and what transport vehicles can move it. Mobility of a tank is categorised as either Battlefield Mobility, Tactical Mobility, or Strategic Mobility. The first is a function of its engine performance and capability of its running gear and is determined by aspects such as acceleration, speed, vertical obstacle capability and so on. The second is the ability of the tank to be readily transported within a theatre of operation. The third is its ability to be transported from one theatre of operation to other, dependent on its weight, air portability and so on. A main battle tank is designed to be very mobile and able to tackle most types of terrain. Its wide tracks disperse the heavy weight of the vehicle over a large area, resulting in a specific ground pressure that might be lower than that of a man's foot. The types of terrain that do pose a problem are usually extremely soft ground such as swamps, or rocky terrain scattered with large boulders. In "normal" terrain, a tank can be expected to travel at about 30 to 50 km/h. The road speed may be up to 70 km/h. The logistics of getting from point A to point B are not as simple as they appear. On paper, or during any test drive of a few hours, a single tank offers better off-road performance than any wheeled fighting vehicle. On the road the fastest tank design is not much slower than the average wheeled fighting vehicle design. But in practice, the huge weight of the tank combined with the relative weakness of the track assembly makes the maximum road speed of a tank really a burst speed, which can be kept up for only a short time before there is a mechanical breakdown. Although the maximum off-road speed is lower, it cannot be kept up continuously for a day, given the variety and unpredictability of off-road terrain (with the possible exception of plains and sandy deserts). Since an immobilised tank is an easy target for mortars, artillery, and the specialised tank hunting units of the enemy forces, speed is normally kept to a minimum, and every opportunity is used to move tanks on wheeled tank transporters and by railway instead of under their own power. Tanks invariably end up on railcars in any country with a rail infrastructure, because no army has enough wheeled transporters to carry all its tanks. Planning for railcar loading and unloading is crucial staff work, and railway bridges and yards are prime targets for enemy forces wishing to slow a tank advance. When moving in a country or region with no rail infrastructure and few good roads, or a place with roads riddled by mines or frequent ambushes, the average speed of advance of a tank unit in a day is comparable to that of a man on a horse or bicycle. Frequent halts must be planned for preventive maintenance and verifications in order to avoid breakdowns during combat. This is in addition to the tactical halts needed so that the infantry or the air units can scout ahead for the presence of enemy antitank groups. Another mobility issue is getting the tank to the theatre of operations. Tanks, especially main battle tanks, are extremely heavy, making it very difficult to airlift them. Using sea and ground transportation is slow, making tanks problematic for rapid reaction forces. Some tank-like vehicles use wheels instead of tracks in order to increase road speed and decrease maintenance needs. These vehicles lack the superior off-road mobility of tracked vehicles, but are considered by United States planners as more suited for rapid reaction forces due to increased strategic mobility.
Water operations
For most tanks water operations are limited to fording. The fording depth is usually limited by the height of the air intake of the engine, and to a lesser extent the driver's position. Typical fording depth for MBTs are 90 to 120 cm.
Deep fording
However, with preparation some tanks are able to ford considerably deeper depths. The West German Leopard I and Leopard II tanks can ford to a depth of several metres, when properly prepared and equipped with a snorkel. The Leopard snorkel is in fact a series of rings which can be stacked to create a long tube. This tube is then fitted to the crew commander's hatch and provides air and a possible escape route for the crew. The height of the tube is limited to around three meters. Some Russian/Soviet tanks are also able to perform deep fording operations, however unlike the Leopard, the Russian snorkel is only a few inches round and does not provide a crew escape path. Russian snorkels are also fixed in length, providing only a couple of metres of depth over the turret height. This type of fording requires careful preparation of the tank and the ingress and egress sites on the banks of the water obstacle. Tank crews usually have a negative reaction towards deep fording. This has influenced tactics in those countries where the psychological health of the crews or their capacity for rebellion is taken into account. However if properly planned and executed this type of operation adds considerable scope for surprise and flexibility in water crossing operations.
Amphibious tanks
Some light tanks such as the PT-76 are amphibious, typically being propelled in the water by hydrojets or by their tracks. Often a fold down trim vane is erected to stop water washing over the bow of the tank and thus reducing the risk of the vehicle being swamped via the driver's hatch. In World War II the M4 Medium (Sherman) tank was made amphibious with the addition of a rubberised canvas screen to provide additional buoyancy. It was propelled by propellers driven by the main engine. This was referred to as the Sherman DD (Duplex Drive) and was used on D-Day to provide close fire support on the beaches during the initial landings. The Sherman DD could not fire when afloat as the buoyancy screen was higher than the gun. A number of these DDs sank due to rough weather in the Channel (having been launched too far out). Those that did make it ashore, however, provided essential fire support in the first critical hours, getting off the beaches.
Power plants
D-Day, 4th Tank Battalion, 4th Marine Division, US Marines.]] The tank's power-plant supplies power for moving the tank and for other tank systems, such as rotating the turret or electrical power for a radio. Tanks fielded in WWI all used petrol (gasoline) engines as power-plants. In the Second World War there was a mix of power-plant types used; a lot of tank engines were adapted aircraft engines. As the Cold War started, tanks had almost all switched over to using diesel, improved multi-fuel versions of which are still common. Starting in the late 1970s, turbine engines began to appear. The weight and type of power-plant (influenced by its transmission and drive train) largely determines how fast and mobile the tank is, but the terrain effectively limits the maximum speed of all tanks through the stress it puts on the suspension and the crew.
Multi-fuel diesels
All modern non-turbine tanks use a diesel engine because diesel fuel is less flammable and more economical than petrol. Some Soviet tanks used the dark smoke of burning diesel as an advantage and could intentionally burn fuel in the exhaust to create smoke for cover. Fuel tanks are commonly placed at the rear of the tank, though in some designs, such as the Israeli Merkava, the diesel fuel tanks are placed around the crew area to provide an additional layer of "armour." Fuel has often been stored in auxiliary tanks externally, or by other means such as in a small trailer towed behind the tank, able to be detached during combat. Modern tank engines are in some cases multi-fuel engines, which can operate on diesel, petrol or similar fuels.
Gas turbines
Gas turbine engines have been used as an auxiliary power unit (APU) in some tanks, and are the main power plant in the Soviet/Russian T-80 and U.S. M1 Abrams. They are comparatively lighter and smaller than diesel engines, at the same level of sustained power output (the T-80 was dubbed the Flying Tank for its high speed). However they are much less fuel efficient, especially at low RPMs, requiring larger fuel tanks to achieve the same combat range. Newer models of the M1 have a small secondary turbine engine as an APU to power the tank's systems while stationary, saving fuel by reducing the need to idle the main turbine. T-80 tanks are commonly seen with large external fuel tanks to extend their range. Russia has replaced T-80 production with the less powerful T-90 (based on the T-72), while Ukraine has developed the diesel-powered T-80UD and T-84 with nearly the power of the gas-turbine tank. Because of their lower efficiency, the thermal signature of a gas turbine is higher than a diesel engine at the same level of power output. On the other hand the acoustic signature of a tank with a muffled gas turbine can be quieter than a piston engine–powered one. The M1A2 was nicknamed Whispering Death for its quiet operation.[http://www.globalsecurity.org/org/news/2003/030324-whispering-death01.htm] A turbine is theoretically more reliable and easier to maintain than a piston-based engine, since it has a simpler construction with fewer moving parts. In practice, however, those parts experience a higher wear due to their higher working speeds. The turbine blades are also very sensitive to dust and fine sand, so that in desert operations special filters have to be carefully fitted and changed several times daily. An improperly fitted filter, or a single bullet or piece of shrapnel can render the filter useless, potentially damaging the engine. Piston engines also need well-maintained filters, but they are more resilient if the filter does fail. Like most modern diesel engines used in tanks, gas turbines are usually multi-fuel engines.
Sonic, seismic, and thermal traces
M1 Abrams Stationary tanks can be well camouflaged in woodland and forested areas where there is natural cover, making detection and attack from the air more difficult. By contrast, in the open it is very hard to hide a tank. In both cases, however, once a tank starts its engine or begins to move it can be detected much more easily due to the heat and noise generated by its engine. The tank tracks across lands can be spotted from the air, and in the desert movement can stir up vast dust clouds several times the size of the tanks. A recently stopped stationary tank has a considerable heat signature. Indeed even if the tank itself is hidden, for example behind a hill, it is still possible for a skilled operator to detect the tank from the column of warmer air above the tank. This risk can be reduced somewhat by the use or thermal blankets which reduce the radiation of heat while the engine and tracks cool. Some camouflage nets are manufactured from unevenly distributed mix of materials with differing thermal properties, which are designed to "randomise" or at least reduce the regularity of the thermal signature of a tank. Tanks are powered by a diesel or turbine engine of a power comparable to a diesel locomotive. From the outside a diesel powered tank smells, sounds, and feels quite like a diesel locomotive. The deep rumble of even a single tank can be heard a great distance on a quiet day, and the sharp diesel smell can be carried far downwind. When a tank stands still with engine running the land trembles around it. When moving, the vibrations are greater. The acoustic and seismic signatures of multi-fuel engines are comparable. The acoustic signature of a turbine engine is much greater: its high-pitched whine can be much more easily distinguished from other sounds, near or far. The very large power output of modern tank engines (typically in excess of 750kW or 1,000hp) ensure that they produce a distinct thermal signature. The unusually compact mass of metal of the tank hull dissipates heat in a fashion which marks it off sharply from other objects in the countryside. A moving tank is thus relatively easy to spot by good land-based or aerial infrared scanners. One of the reasons for the one-sided fighting during the Gulf Wars was that tanks like M1 Abrams had almost four times the night-time infrared scanning range of T-72s used by the Iraqi army. Another factor in the Gulf War was that, even when camouflaged and not moving, Iraqi tanks at night would cool at a different rate from their surroundings, making thermal detection easier. Getting a tank to move proved to be important in the Kosovo conflict in 1999. During the initial few weeks of the conflict NATO air sorties were rather ineffective in destroying Serbian tanks. This changed in the final week of the conflict, when the Kosovo Liberation Army began to engage tanks. Although the KLA had little chance of destroying the tanks, their purpose was to get the tanks to move whereupon they could be more easily identified and destroyed by NATO air power.
Command, control, and communications
Commanding and co-ordinating a tank organisation in the field has always been subject to particular problems. Because of the isolation of small units, individual vehicles, and even the crewmen of a tank, special arrangements have had to be made. Armoured bulkheads, engine noise, intervening terrain, dust, and smoke, and the need to operate "hatches down" (or "buttoned up") comprise severe detriments to communications. Every action of a tank's crew, movement and fire, is ordered by its commander. In some early tanks, the crew commander's task was severely hampered by having to load or fire the main armament, or both. In many small armoured fighting vehicles, even into the late twentieth century, the crew commander would relay movement orders to the driver by kicks to his shoulders and back. Most modern AFVs are equipped with an intercom, allowing all crew members to talk to each other, and to operate the radio equipment. Some tanks have even been equipped with an external intercom on the rear, to allow co-operating infantry to talk to the crew. In the earliest tank operations, communications between the members of an armoured company were accomplished using hand signals or handheld semaphore flags, and in some situations, by crew members dismounting and walking to another tank. In World War One, situation reports were sent back to headquarters by releasing carrier pigeons through vision slits. Signal flares, smoke, movement, and weapons fire are all used by experienced crews to co-ordinate their tactics. From the 1930s to the '50s, most nations' armoured forces became equipped with radios, but visual signals are still used to reduce radio chatter. A modern tank is usually equipped with radio equipment allowing its crew to communicate on a company or battalion radio network, and possibly to monitor a higher-level network, to co-ordinate with other arms of service. Company or battalion commanders' tanks usually have an additional radio. Communications on a busy network are subject to a set of formalised language rules called radio voice procedure. Most armoured forces operate with the crew commander, and possibly other crew members, "hatches up", for best possible situational awareness. When taking fire, or in potential NBC conditions, tank crews "button up" and only view the battlefield through vision slits or periscopes, severely reducing their ability to acquire targets and perceive hazards. Since the 1960s, a tank's commander has had progressively more sophisticated equipment for target acquisition. In a main battle tank, the commander has his own panoramic sights (with night-vision equipment), allowing him to designate one or more new targets, while the gunner engages another. More advanced systems allow the commander to take control of the turret and fire the main armament in an emergency. A recent development in AFV equipment is the increased integration of fire control, the laser range-finder, GPS data, and digital communications. U.S. tanks are fitted with digital computers which are connected into battlefield networks. These integrate known information on enemy targets and friendly units to greatly improve the tank commander's situational awareness. In addition to easing the reporting burden, these systems also allow for orders to be given complete with graphics and overlays, via the network.
See also

- Military communications
- Command, control, and communications (C3I)
Vulnerability
Whilst being a tremendously powerful weapon and the undoubted king of the land battlefield, the tank is not invulnerable. In fact it is the tank's superiority which has focused so much effort on improving antitank weapons.
Infantry
The tank is still vulnerable to infantry, especially in close country or built up areas. The armour and mobility of tanks, while usually notable assets, also makes them large and noisy. This can give enemy infantry the initiative, allowing them to spot, track and evade tanks until an opportunity presents itself for a stealthy counter-attack. This is why modern tactics insist on tanks being closely supported by friendly infantry. For veteran troops, it is relatively easy for an infantry man to get close to a tank, especially if it is fully closed down (that is, the commander is fully inside the turret) as tanks have very poor visibility close in and especially to the sides and rear, unless the turret is pointing in that direction. If the crew commander is not closed down, that is, has exposed his head and perhaps upper body for the better view it affords him, then he can of course be shot. In theory, it is easy for an infantry man to lie prone, wait behind a tree or other handy cover or inside a building and to quickly dash out as a tank passes. However, the tank is a fearsome war machine; it takes confidence, discipline and training to carry this out. Once an infantry man is close to a tank he is invulnerable unless the crew expose themselves to attack him as the main gun and coaxial machine gun can not depress sufficiently to engage the close in infantry man. Where tanks are operating in groups this is less of a problem, since they can call on nearby tanks to fire on themselves with machine guns and other light weapons which are unlikely to damage a tank but which will drive off infantry. Whilst many handheld infantry antitank rockets, missiles and grenades will not penetrate the front armour of a tank, they will, generally speaking, penetrate the weaker, rear, top and perhaps sides, as well as being able to easily damage the running gear to inflict an "M" (mobility) kill. Tanks are also vulnerable to hand placed antitank mines. In addition in built up areas the tank is very vulnerable to attack from above—the roof and floor of the tank being traditionally the thinnest and weakest armoured surfaces.
Artillery
Traditionally, conventional artillery has not been very effective against tanks as the tank's armour could withstand any artillery round except a direct hit. Even though a shell may not penetrate a tank's armour, it can still disable it through dynamic shock, internal armor shattering, or simply overturning the tank. In the last thirty years however, a variety of artillery projectiles have been developed with attacking tanks in mind. These include laser guided projectiles, such as the US Copperhead CLGP (Cannon Launched Guided Projectile) which virtually guarantee a direct hit on the thin top armour. In addition some of these CLGP's such as the Copperhead have HEAT warheads instead of common HE. In addition to achieving a direct hit with guided projectiles, guided and unguided scatter munitions and submunitions have been developed: a single artillery shell containing a number of smaller munitions designed to attack a tank. At its simplest the shell bursts in the air and a number of shaped charged (HEAT) or HEDP (High Explosive Dual Purpose) bomblets or grenades rain down, with luck hitting the tank. If they do hit they will likely cause damage, despite their small size, since they are attacking the thin top armour. A variation on this theme is replacing the top attack munitions with small antitank mines, which probably won't penetrate the armour but will blow off a track, leaving the tank vulnerable for destruction by other means. A six-gun battery might be able to fire several hundred submunitions into an area in a minute or two. More sophisticated are submunitions with a homing capability. Once again the shell explodes above the tank position and dispenses a (usually smaller) number of submunitions. The munitions contain some circuitry to identify tanks, such as IR or millimetre radar. In order to allow the munition time to use its sensor the munition will often be deployed under a parachute. When a tank is identified a rocket is fired to direct the projectile at the tank. All of the above bar the CLGP can be fired from medium (152/155-mm) artillery, both tube and rocket. There has also been development of large calibre (81-mm and larger) guided mortar munitions with both internal (e.g., IR or radar) or external (i.e. laser designator) guidance for attacking tanks. See also Anti-tank#anti-tank guns.
Helicopters
The single biggest threat to the tank today is the antitank helicop

WWII

, and the use of new, extremely devastating weapons such as the atom bomb. From top going counterclockwise: Allied landing on D-Day 1944, the Nuremberg Rally 1936, the Nagasaki atom bomb 1945, the Soviet flag over the Reichstag in Berlin 1945 and the Gate of Auschwitz.]] World War II, also known as the Second World War, was a mid-20th Century conflict that engulfed much of the globe and is accepted as the largest and deadliest continuous war in human history. It was the first time that a number of newly developed technologies, including nuclear weapons, were used against either military or civilian targets. World War II resulted in the direct or indirect death of anywhere from 50 to 60 million or more people, over 3% of the world population at that time. It is estimated to have cost more money and resources than all other wars combined: about 1 trillion US dollars in 1945 (adjusted for inflation; roughly 10.5 trillion in 2005), not including subsequent reconstruction [http://www.historychannel.com/worldwartwo/?page=triumph5]. The outcomes of the war, including new technology and changes to the world's geopolitical, cultural and economic arrangement, were unprecedented. The conflict began by most Western accounts on September 1 1939 with the German invasion of Poland (the Pacific war is taken to have started on July 7 1937 with the Japanese attack on China) and lasted until mid-1945, involving many of the world's countries. Virtually all countries that participated in World War I were involved in World War II. Britain, France, Australia and New Zealand declared war on Germany on September 3, 1939 and Canada followed on September 10, 1939. The United States entered the conflict in December of 1941 after the Japanese attack on Pearl Harbor.

Summary

Attributed in varying degrees to the Treaty of Versailles, the Great Depression, and the rise in nationalism, racism, fascism, National socialism, Japanese imperialism, and militarism, the causes of the war are a matter of debate. The war was fought between the Axis Powers and the Allies. The Axis initially consisted of an alliance between Germany and Italy, which later expanded to include Japan and Eastern European countries such as Romania and Bulgaria. Some of the nations that Germany conquered sent military forces, particularly to the Eastern front. Among the expeditionary forces that joined Germany were forces from Vichy France, The Netherlands, Belgium, Spain (though Spain was itself a neutral country) and armies of Russians and Ukrainians under the command of the general Andrey Vlasov. The Allies were initially the United Kingdom, including the Commonwealth, France and Poland, later joined by the USSR, the United States of America and China. Fighting occurred across the Atlantic Ocean, in Western and Eastern Europe, in the Mediterranean Sea, Africa, the Middle East, in the Pacific and South East Asia, and it continued in China. In Europe, the war ended with the surrender of Germany on 8 May 1945 (V-E and Victory Days), but continued in Asia until Japan surrendered on 15 August 1945 (V-J Day). At least 50 million people died as a result of the war. This figure includes acts of genocide such as the Holocaust and General Ishii Shiro's Unit 731 experiments in Pingfan, incredibly bloody battles in Europe and the Pacific Ocean, and massive bombings of cities, including the atomic bombings of Hiroshima and Nagasaki in Japan and the firebombing of Dresden (and even worse but less known) of Pforzheim in Germany. Few areas of the world were unaffected; the war involved the "home front" and bombing of civilians to a new degree. Atomic weapons, jet aircraft, rockets and radar, the blitzkrieg, or "lightning war", the massive use of tanks, submarines, torpedo bombers and destroyer/tanker formations, are only a few of many wartime inventions and new tactics that changed the face of the conflict. Post–World War II Europe was partitioned into Western and Soviet spheres of influence, the former undergoing economic reconstruction under the Marshall Plan and the latter becoming satellite states of the Soviet Union. This partition was, however, informal; rather than coming to terms about the spheres of influence, the relationship between the victors steadily deteriorated, and the military lines of demarcation finally became the de facto country boundaries. Western Europe largely aligned as NATO, and Eastern Europe largely as the Warsaw pact countries, alliances which were fundamental to the ensuing Cold War. In Asia, the United States' military occupation of Japan led to Japan's democratisation. China's civil war continued through and after the war, resulting eventually in the establishment of the People's Republic of China. The war sparked a wave of independence for colonies of European powers, who were exhausted from fighting the war. There was a fundamental shift in power from Western Europe to the new superpowers, the United States and the Soviet Union, though there were few actual boundary changes. __TOC__

Causes

People's Republic of China]] Main articles: Causes of World War II, Events preceding World War II in Europe, Events preceding World War II in Asia The causes of World War II are naturally a debated subject, but a common view, particularly among the allies in the early post-war years, ties them to the expansionism of Germany and Japan: Germany had lost wealth, power and status following the First World War and the expansion was to make Germany great again.
- In Germany there was a strong desire to escape the bonds of the World War I Treaty of Versailles, and eventually, Hitler and the Nazis assumed control of the country. They led Germany through a chain of events: rearmament, reoccupation of the Rhineland, a merger with Austria (Anschluss), incorporation of Czechoslovakia and finally the invasion of Poland.
- In Asia, Japan's efforts to become a world power and the rise of militarist leadership (in the 1930s the government in Japan was undermined as militarists rose to power and de facto gained totalitarian control) led to conflicts with first China and later the United States. Japan also sought to secure additional natural resources, such as oil and iron ore, due in part to the lack of natural resources on Japan's own home islands.

Participants

iron ore and Joseph Stalin, during the Yalta Conference in 1945]] Main article: Participants in World War II The belligerents of the Second World War are usually considered to belong to either of the two blocs: the Axis and the Allies. A number of smaller countries participated in the war, though often under occupation or as proxies of one of the large powers. The Axis Powers consisted primarily of Germany, Italy, and Japan, which split the Earth into three spheres of influence under the Tripartite Pact of 1940, and vowed to defend one another against aggression. This replaced the German-Japanese Anti-Comintern Pact of 1936 that Italy had joined in 1937. Spain's fascist government led by Francisco Franco was a great asset in trade to the Axis powers during the war. A number of smaller countries were counted among the Axis powers. Among these were Bulgaria, Romania, Hungary, Slovenia, and arguably Finland. Among the Allied powers, the so-called Big Three were the United Kingdom (from September 3 1939), the Soviet Union (from June 1941) and the United States (from December 1941). China had been at war with Japan since 1937. 1937 On August 23, 1939, just before the war broke out, the USSR and Germany signed the non-aggression Molotov-Ribbentrop Pact, which, among other things, divided Eastern Europe into regions of influence. But Germany violated the pact when it invaded the USSR in 1941. Similarly, the US had the (much older) unilateral Monroe Doctrine, which stated that Europe should not interfere in the Americas and in turn the U.S. would not interfere in European affairs (including wars). But the U.S. entered the war after first Japan and then Germany declared war on it and launched direct attacks on its navy, shipping and other interests. Many other countries, including Australia, Belgium, Brazil, Canada, Denmark, France, Greece, the Netherlands, New Zealand, Norway, the Philippines, Poland, Thailand and Yugoslavia are also considered important Allies, although some of these were conquered and occupied by Axis forces or even officially joined the Axis as a result of coercion. Countries that attempted to remain neutral in the conflict were often viewed with suspicion by the participants, and often pressured to make contributions to the most influential power in their neighbourhood. Sovereignty was often difficult to maintain as many countries that did not directly participate in the conflict nevertheless held vested interests in seeing a particular side prevail. For example, neutral Switzerland was generally considered to be "Allied-friendly", while neutral Spain was considered "Axis-friendly", despite the fact that neither country openly proclaimed any alliances. Such situations allowed neutral countries to become hotbeds of espionage. It is important to note as well, that Sweden's participation in the war was negligable due to specific relations with the German state at the time.

A debated starting date

On which date World War II started is a debated subject; historians do not all agree on which event signified the start of the war. The most common date used is 1 September 1939, marking the German invasion of Poland which resulted in the British and French declarations of war two days later. Other candidates include the Japanese invasion of China on 7 July 1937 (the start of the Second Sino-Japanese War) or the entry of Hitler's armies to Prague in March 1939. Some historians argue that the Italian occupation of Ethiopia (The Second Italo-Abyssinian War) which lasted seven months in 1935-1936 was the actual start of World War II. There are some historians that argue the war started on the start of the Manchurian Incident on 18 September 1931.

Chronology 1937-45

Main articles: European Theatre of World War II, Mediterranean Theatre of World War II, Pacific War, End of World War II in Europe

1937: Second Sino-Japanese War

On 7 July 1937, Japan, after occupying northeastern China as Manchuria in 1931, launched another attack against China near Beijing (see Marco Polo Bridge Incident). Rather than retreating swiftly as in engagements with the Japanese before, the Chinese government declared war on Japan, marking the official start of the Second Sino-Japanese War, which would soon become part of the World War. In December 1937, the capital, Nanking (now Nanjing), fell and the Chinese government moved its seat to Chongqing for the rest of the war. Surprised by the unanticipated level of resistance from China, the Japanese forces committed brutal atrocities against civilians and POWs when Nanking was occupied (see Nanjing Massacre), killing up to 200,000 civilians within a month. In Europe, the peace was uneasy, with Germany annexing Austria and Czechoslovakia, and taking apparent aim at Poland.

1939: War breaks out in Europe

Poland]] Main articles: Polish September Campaign, Phony War War broke out in Poland on 1 September 1939, with the German invasion of Poland. France and the United Kingdom honoured their defensive alliance of March 1939 by declaring war two days later on 3 September. Australia and New Zealand declared war the same day, although through the quirk of the international date line, New Zealand then Australia were the first to declare war on Germany. Canada followed a week later, on 10 September. Only partly mobilised and with troops inadequately equipped with largely outdated weapons (which included large numbers of horse-mounted cavalry), and without the anticipated support of French or British forces, Poland unsurprisingly fared poorly against the Wehrmacht's superior numbers and "blitzkrieg" tactics. In accordance with the Molotov-Ribbentrop Pact, the Soviet Red Army invaded Poland from the east on 17 September. Hours later, the Polish government escaped to Romania. The last Polish Army unit was defeated on 6 October. As Poland fell, the British and French were either caught unaware of German intentions or had not allowed themselves to believe that Germany would invade Poland. Germany paused to regroup during a period that would be termed "the Phony War", or the "Sitzkrieg", which lasted until May 1940. Polish forces continued to fight the Axis powers after their country fell. A prominent example was the assistance of Polish pilots during the Battle of Britain. The Soviet Union, due to its treaty relationship with Nazi Germany, did not fight the fascists: Stalin was happy to have those he felt were his natural and true enemies—the capitalist West and Nazi Germany—fight each other. Indeed, the Soviets had their partisans in the U.S., working alongside Nazi sympathisers, advocate that the U.S. remain neutral in the war, a position that the majority of Americans, reluctant to join in what they saw as "someone else's war," welcomed. Battle of Britain There were isolated engagements during the "Phony War" or "Sitzkrieg" period, including the sinking of HMS Royal Oak in the anchorage at Scapa Flow and Luftwaffe bombings of the naval bases at Rosyth and Scapa Flow. The Kriegsmarine pocket battleship Admiral Graf Spee was sunk in South America after the battle of the River Plate. The Tripartite Pact was signed between Germany, Italy, and Japan on 27 September, 1940, formalising their alignment as the "Axis Powers". The Soviet Union invaded Finland on 30 November 1939, beginning the Winter War, which lasted until March 1940 with Finland ceding territory to the Soviet Union.

1940: The war spreads

Winter War Main Articles: Norwegian Campaign, Battle of France, Battle of Britain, North African Campaign, Balkans Campaign Europe: Germany invaded Denmark and Norway on 9 April 1940, in Operation Weserübung, ostensibly to counter the threat of an Allied invasion from the region. Heavy fighting ensued on land and at sea in Norway. British, French and Polish forces landed to support the Norwegians at Namsos, Åndalsnes and Narvik, with most success at the latter. By late June, all Allied forces had been evacuated, and the Norwegian Army surrendered. France, Belgium, the Netherlands and Luxembourg were invaded on 10 May, ending the Phony War and beginning the Battle of France. The Allies had hoped to establish a static continuous front and were ill-prepared for the German Blitzkrieg tactics. In the first phase of the invasion, Operation Yellow, the Wehrmacht's Panzergruppe von Kleist bypassed the Maginot Line and split the Allies in two by driving to the English Channel. Belgium, Luxembourg, and the Netherlands fell quickly against the attack of Army Group B, and the British Expeditionary Force, trapped in the north, was evacuated at Dunkirk in Operation Dynamo. German forces then invaded France itself, in Operation Red, advancing behind the Maginot Line and near the coast. While some units from the French army were still fighting, a number of top politicians and military leaders decided that it would be better to surrender given the situation; France signed an armistice with Germany on June 22 1940, leading to the establishment of the Vichy France puppet government in the unoccupied part of France. In June 1940 the Soviet Union occupied Latvia, Lithuania and Estonia, and annexed Bessarabia and Northern Bukovina from Romania. Not having secured a rapid peace with the United Kingdom, Germany began preparations to invade with the Battle of Britain. Fighter aircraft fought overhead for months as the Luftwaffe and Royal Air Force fought for control of Britain's skies. The Luftwaffe initially targeted RAF Fighter Command but turned to terror bombing London. The Luftwaffe was not successful, and Operation Sealion, the proposed invasion of the British Isles, was abandoned. Similar efforts were made, though at sea, in the Battle of the Atlantic. In a long-running campaign, German U-Boats attempted to deprive the British Isles of necessary Lend Lease cargo from the United States. The U-Boats reduced shipments considerably; however, the United Kingdom refused to seek peace, with Prime Minister Winston Churchill stating that "We shall never surrender". President Roosevelt announced a shift in the American stance from neutrality to "non-belligerency". The Mediterranean: Italy invaded Greece on 28 October 1940, from bases in Albania. Although outnumbered, Greek forces successfully repelled the Italian attacks and launched a full-scale counter-attack deep into Albania. By mid-December they had liberated one-fourth of Albania. The North African Campaign began in 1940; Italian forces in Libya attacked British forces in Egypt. The aim was to make Egypt an Italian possession, especially the vital Suez Canal. British, Indian and Australian forces counter-attacked (see Operation Compass), but this offensive stopped in 1941 when much of the Commonwealth forces were transferred to Greece to defend it from German attack. However, German forces (known later as the Afrika Korps) under General Erwin Rommel landed in Libya and renewed the assault on Egypt. Italian troops invaded and captured British Somaliland in August 1940. On the other hand, the Italian declaration of war challenged the British supremacy of this sea, a supremacy hinged on Gibraltar, Malta and Alexandria. While Gibraltar was never under direct attack, Alexandria and to a deadlier degree Malta were hit repetitively by Axis attacks, the thrusts towards the Suez Canal for the former, and the 1940/42 Blitz for the latter, which made the island of Malta the most heavily bombed place on earth. Asia: In 1940, Japan occupied French Indochina (Vietnam) upon agreement with the Vichy Government, despite local Free French, and joined Axis powers Germany and Italy. These actions intensified Japan's conflict with the United States and the United Kingdom, which reacted with an oil boycott.

1941: The war becomes global

Main articles: Eastern Front, Continuation War, Attack on Pearl Harbor Europe: Attack on Pearl Harbor Yugoslavia's government succumbed to the pressure of Italy and Germany and signed the Tripartite Treaty on 25 March 1941. This was followed by anti-Axis demonstrations in the country and a coup which overthrew the government and replaced it with a pro-Allied one on 27 March 1941. Hitler's forces then invaded Greece and Yugoslavia on 6 April 1941. Hitler reluctantly sent forces to assist Mussolini's forces in their attempt to capture Greece, principally to prevent a British build-up on Germany's strategic southern flank. With these new troops the Axis succeeded in driving the Greek forces back. British troops were diverted from North Africa to assist with the defence but failed to prevent Greece's capture. On 20 May 1941, the Battle of Crete began when elite German paratroopers and glider-borne mountain troops and some 1300 aeroplanes launched a massive airborne invasion of the Greek island of Crete. Crete was defended by an group of about 43,000 Greek, New Zealand, Australian and British troops, not all of them fully equipped. The Germans attacked the island simultaneously on the three airfields. Their invasion on two of the airfields failed, but they successfully captured one, which allowed them to reinforce their position by landing reinforcements. After a week it was decided that so many German troops had been flown in that there was no way to defeat them, and about 17,000 Commonwealth soldiers were evacuated. However, over 10,000 Greek and 500 Commonwealth troops remained at large and caused problems for the German occupiers. The Germans may have suffered well over 15,000 casualties. So heavy were the losses that Hiler decided never to launch an airborne invasion again. General Kurt Student would later say, "Crete was the grave of the German parachutists". The Allies, on the other hand, came to the conclusion that every major invasion should be supported by paratroopers. Operation Barbarossa, the German invasion of the Soviet Union, the largest invasion in history, commenced on 22 June 1941. The "Great Patriotic War" (Russian: Великая Отечественная Война, Velikaya Otechestvennaya Voyna) had begun with surprise attacks by German panzer armies, which encircled and destroyed much of the Soviet's western military, capturing or killing hundreds of thousands of men. Soviet forces came to fight a war of scorched earth, withdrawing into the steppe of Russia to acquire time and stretch the German army. Industries were dismantled and withdrawn to the Ural mountains for reassembly. German armies pursued a three-pronged advance against Leningrad (modern-day St Petersburg), Moscow, and the Caucasus. Having pushed to occupy Moscow before winter, German forces were delayed into the Soviet Winter. Soviet counter-attacks defeated them within sight of Moscow's spires, and a rout was only narrowly avoided. Some historians identify this as the "turning point" in the Allies' war against Germany; others identify the capitulation of the German Sixth Army outside Stalingrad (modern-day Volgograd) in 1943. The Continuation War between Finland and the Soviet Union began with Soviet air attacks shortly after the beginning of Operation Barbarossa, on 25 June, and ended with an armistice in 1944. The Soviet Union was joined in the war by the United Kingdom but not by the United States. The Mediterranean again: In June 1941, Allied forces invaded Syria and Lebanon, capturing Damascus on 17 June (see Syria-Lebanon campaign). Meanwhile, Rommel's forces advanced rapidly eastward, laying siege to the vital seaport of Tobruk. Australian and other Allied troops in the city resisted all until relieved, but a renewed Axis offensive captured the city and drove the Eighth Army back to a line at El Alamein. Asia: The Sino-Japanese War El Alamein Main article: Sino-Japanese War (1937-1945) A war had begun in Asia years before World War II started in Europe. Japan had invaded China in 1931. By 1937, war had broken out as the Japanese sought control of China. Roosevelt signed an unpublished (secret) executive order in May 1940 allowing U.S. military personnel to resign from the service so that they could participate in a covert operation in China: the American Volunteer Group, also known as Chennault's Flying Tigers. Over a seven-month period, Chennault's Flying Tigers destroyed an estimated 600 Japanese aircraft, sunk numerous Japanese ships, and stalled the Japanese invasion of Burma. With the United States and other countries cutting exports to Japan, particularly fuel oil, Japan planned a strike on Pearl Harbor on Sunday, 7 December 1941, to cripple the U.S. Pacific Fleet while consolidating oil fields in Southeast Asia. It is hard to determine whether the Japanese intended to release an advance declaration of war, however, as means of coordinating secret directives with public communication, particularly during a weekend in the U.S., were limited. Despite what warning signs remained, the attack on Pearl Harbor achieved military surprise and dealt severe damage to the American Fleet's battleships, though the primary targets, aircraft carriers, remained safely at sea. The next day, Japanese forces arrived at Hong Kong, which later led to the surrender of the British colony on Christmas Day (known to locals as 'Black Christmas'), as well as launching numerous attacks on British and American outposts across the Pacific. Asia: The United States enters the war
Main article: Attack on Pearl Harbor Attack on Pearl Harbor On 7 December 1941, Japanese warplanes commanded by Vice Admiral Chuichi Nagumo carried out a surprise air raid on Pearl Harbor, the largest U.S. naval base in the Pacific. The Japanese forces met little resistance and devastated the harbour. This attack resulted in 8 battleships either sunk or damaged, 3 light cruisers and 3 destroyers sunk as well as damage to some auxiliaries and 343 aircraft either damaged or destroyed. However the attack failed to strike targets that could have been crippling losses to the US Pacific Fleet such as the aircraft carriers which were out at sea at the time of the attack or the base's ship fuel storage and repair facilities. The survival of these assets have led many to consider this attack a catastrophic long term strategic blunder for Japan. The following day, the United States declared war on Japan. Simultaneously to the attack on Pearl Harbor, Japan also attacked U.S. air bases in the Philippines. Immediately following these attacks, Japan invaded the Philippines and also the British Colonies of Hong Kong, Malaya, Borneo and Burma with the intention of seizing the oilfields of the Dutch East Indies. In a matter of months, all these territories and more fell to the Japanese onslaught. The British island fortress of Singapore was captured in what Churchill considered one of the most humiliating British defeats of all time. Following the Japanese attack on Pearl Harbor, Germany declared war on the United States on 11 December 1941, even though it was not obliged to do so under the Tripartite Pact of 1940. Hitler made the declaration in the hopes that Japan would support him by attacking the Soviet Union. Japan did not oblige him, and this diplomatic move proved a catastrophic blunder which gave President Franklin D. Roosevelt the pretext needed for the United States joining the fight in Europe with full commitment and with no meaningful opposition from Congress. Some historians mark this moment as another major turning point of the war with Hitler provoking a grand alliance of powerful nations, most prominently the UK, the USA and the USSR, who could wage powerful offensives on both East and West simultaneously.

1942: Deadlock

Franklin D. Roosevelt] Main articles: Battle of Stalingrad, Operation Torch Europe: In 1942, an aborted German offensive was launched towards the Caucasus to secure oil fields, and German armies reached Stalingrad. The siege of Stalingrad continued for many months, with vicious urban warfare leading to high casualties on both sides. At night, the Soviet forces were resupplied from the east bank of the Volga, and the Wehrmacht forces were eventually ground down; especially after Hitler diverted the armour of the Sixth Army to the Caucasus. In November a Soviet offensive encircled Sixth Army. By early February 1943, it was clear that the Sixth Army would have to surrender. Hitler promoted General Friedrich Paulus, who was in charge of the German forces, to Field Marshal in the vain hope it would deter him from surrendering. It did not, and he surrendered completely on 2 February. The results were the destruction of the city, millions of casualties, and the collapse of Germany's Sixth Army as a viable fighting force. Nazi Propaganda Minister Joseph Goebbels responded with his Sportpalast speech to the German people. Some historians cite this as the European war's "turning point". The Mediterranean: Sportpalast speech Sportpalast speech (432nd Squadron) damaged by flak somewhere over Algeria during the North African Campaign in 1942.]] The First Battle of El Alamein took place between 1 July and 27 July 1942. German forces had advanced to the last defensible point before Alexandria and the Suez Canal. However, they had outrun their supplies, and a Commonwealth defence stopped their thrusts. The Second Battle of El Alamein occurred between October 23 and November 3, 1942, after Bernard Montgomery had replaced Claude Auchinleck as commander of the Commonwealth forces, now known as the Eighth Army. Erwin Rommel, German commander of the Afrika Corps, known as the "Desert Fox", was absent for this battle because he was recovering from jaundice back in Europe. Commonwealth forces took the offensive, and although they lost more tanks than the Germans began the battle with, Montgomery was ultimately triumphant. The western Allies had the advantage of being close to their supplies during the battle. In addition, Rommel was getting little or no help by this time from the struggling Luftwaffe, which was now more tasked with defending Western European air space, and fighting the Soviet Union, than providing Rommel with support in North Africa. After the German defeat at El Alamein, Rommel made a successful strategic withdrawal to Tunisia. During the Arcadia Conference from December 1941 to January 1942, the Allied leaders concluded that it was essential to keep Russia in the war. This consideration led to the overall strategy "Germany First"; i.e. giving priority of knocking out Germany before Japan. This decision resulted in a long debate as to where and when to open a Second Front against Germany. The American Chiefs of Staff favoured a cross-channel (France) amphibious operation in the summer. The British opposed this because of insufficient landing craft and logistical problems. It was also thought that American forces were in a process of expansion, organisation and exercise, not capable yet of fighting an experienced German army. Only if Russia collapsed would they approve a main landing in France. Churchill put forward the idea of a small invasion in Norway or landings in French North Africa. The plan for landings in Africa was approved in July 1942. Operation Torch was headed by General Dwight Eisenhower. The aim of Torch was to gain control of Morocco and Algiers through simultaneous landings at Casablanca, Oran and Algiers, followed a few days later with a landing at Bône, the gateway to Tunisia. The operation was launched on 8 November 1942. The first wave was almost entirely American troops, because it was thought that the French would react more favourably to Americans than British. It was hoped that the local forces of Vichy France would put up no resistance and submit to the authority of Free French General Henri Giraud. In fact, resistance was stronger than expected but still sporadic. In Algiers, 400 members of the French resistance captured much of the city, though it was retaken before Allied forces could arrive. The Vichy commander, Admiral Darlan, negotiated an end to hostilities, against orders from the Vichy government. He was allowed to retain local control by the Allies, to the annoyance of Free French leaders. Hitler invaded and occupied Vichy France in response. Rommel's Afrika Corps was not being supplied adequately because of the loss of transport shipments caused by Allied—mostly British—navies and air forces in the Mediterranean. This lack of supplies and air support destroyed any chance of a large German offensive in Africa. Ultimately, German and Italian forces were caught in the pincers of a twin advance from Algeria and Libya. The withdrawing Germans continued to put up stiff defence, and Rommel defeated the American forces decisively at the Battle of Kasserine Pass before finishing his strategic withdrawal back to the meagre German supply chain. Inevitably, advancing from both the east and west, the Allies finally defeated the German Afrika Corps on May 13 1943. Some 250,000 Axis soldiers were taken prisoner. Asia: 1943]] In May 1942, a naval attack on Port Moresby, New Guinea, was thwarted by Allied navies in the Battle of the Coral Sea. Had the capture of Port Moresby succeeded, the Japanese Navy would have been within striking range of Australia. This was both the first successful opposition to Japanese plans and the first naval battle fought only between aircraft carriers. The two sides suffered roughly equal losses. A month later the invasion of Midway Island was prevented by decoding secret Japanese messages, and hence alerted U.S. naval leaders that Midway was the Japanese target. American pilots sunk four Japanese carriers, which the Japanese industry could not replace swiftly. The loss of many planes and skilled pilots (many of them took part in Pearl Harbor) was also difficult to redress. The Americans lost one carrier and fewer planes. It was a complete victory for the Americans, and the Japanese Navy was now on the defensive. However, in July an overland attack on Port Moresby was led along the rugged Kokoda Track. This was met with Australian militia, many of them very young and undertrained, fighting a stubborn rearguard action until the arrival of Australian regulars returning from action in North Africa, Greece and the Middle East. But amazingly, the outnumbered and untrained Australian 39th battalion defeated the 5,000-strong Japanese army. This was one of the most significant victories in Australian military history. Even prior to the American entry to the war, the Allied leaders had agreed that priority should be given to the defeat of Nazi Germany. Nonetheless, U.S. forces began to attack captured territories, beginning with Guadalcanal Island, against a bitter and determined Japanese defence. On 7 August 1942, the United States assaulted the island. In late August and early September, while battle raged on Guadalcanal, an amphibious Japanese attack on the eastern tip of New Guinea was met by Australian forces at Milne Bay, and the Japanese land forces suffered their first conclusive defeat. On Guadalcanal, the Japanese resistance failed in February 1943. A substantial element of the Asian campaign was played out, starting in 1942, in the Aleutian Islands. For detailed information, see World War II: Ale