The development of tanks in World War I was a response to the stalemate that trench warfare had created on the western front. An initial vehicle, nicknamed Little Willie, was constructed in Great Britain, at William Foster & Co., during August and September, 1915. The prototype of a new design that would become the Mark I tank was demonstrated to the British Army on February 2, 1916. Although initially termed "land ships" by the Landships Committee, production vehicles were named "tanks", to preserve secrecy. The term was chosen when it became known that the factory workers at William Foster referred to the first prototype as "the tank" because of its resemblance to a steel water tank.
While the British took the lead in tank development, the French were not far behind, fielding their first tanks in April, 1917 and going on to produce more tanks than all the other combatants combined. The Germans, on the other hand, were slower to develop tanks, concentrating on anti-tank weapons to use against British and French tanks, and producing only 20 of their own A7V.
The first tanks were highly mechanically unreliable. There were problems that caused considerable attrition rates during combat deployment and transit. The heavily shelled terrain was impassable to conventional vehicles, and only highly mobile tanks such as the Mark and FTs performed reasonably well. The Mark I's rhomboid shape, caterpillar tracks, and 26 feet length meant that it could navigate obstacles, especially wide trenches, that wheeled vehicles could not. Along with the tank, the first self-propelled gun and the first armoured personnel carrier were also introduced in World War I (the Mark V* tank was built with space inside for a small squad of infantry).