Although the tank was developed during the Great War, the armistice came too soon for the potential of the new weapon to be obvious, and the USA showed little interest in it. Some visionary officers still championed its cause, but it was only after the outbreak of war in Europe in 1939, and especially the swift overrunning of France by German Panzer forces in 1940, that the US realised it would need a modern army well-equipped with the latest tanks. Steps were immediately taken to create armoured forces and to provide modern tanks, and over the course of the war in Europe American M4 Shermans and others were the major element of the western allied armies, while they made a less prominent but still important contribution to the war in the Pacific.