Armoured warfare or armored warfare (American English; see spelling differences), is the use of armored fighting vehicles in modern warfare. It is a major component of modern methods of war. The premise of armoured warfare rests on the ability of troops to penetrate conventional defensive lines through use of manoeuvre by armoured units. Much of the application of armoured warfare depends on the use of tanks and related vehicles used by other supporting arms such as infantry fighting vehicles, self-propelled artillery, and other combat vehicles, as well as mounted combat engineers and other support units. The doctrine of armoured warfare was developed to break the static nature of World War I trench warfare on the Western Front, and return to the 19th century school of thought that advocated manoeuvre and decisive battle outcomes in military strategy. World War I Modern armoured warfare began during the First World War of 1914–1918. Strategists wanted to break the tactical, operational and strategic stalemates forced on commanders on the Western Front by the effectiveness of entrenched defensive infantry armed with machine guns – known as trench warfare. Under these conditions, attacks usually advanced very slowly and incurred massive casualties. The developers of tanks aimed to return manoeuvre to warfare, and found a practical way to do so: providing caterpillar traction to machine guns allowing them to overcome trenches, while at the same time offering them armour protection against small-arms (pistol, rifle, and machine gun) fire as they were moving. Britain and France first developed tanks in 1915 as a way of navigating the barbed wire and other obstacles of no-man's land while remaining protected from machine-gun fire. British Mark I tanks first went into action at the Somme on 15 September 1916, but did not manage to break the deadlock of trench warfare. The first French employment of tanks, on 16 April 1917, using the Schneider CA, also failed to live up to expectations. In the Battle of Cambrai (November to December 1917) British tanks were more successful, and broke a German trenchline system, the Hindenburg Line. Despite the generally unpromising beginnings, the military and political leadership in both Britain and France during 1917 backed large investment into armoured-vehicle production. This led to a sharp increase in the number of available tanks for 1918. The German Empire, on the contrary, produced only a few tanks, late in the war. Twenty German A7V tanks were