Army

In World War II mobility returned to warfare; tanks and bombers broke through defences in the German blitzkrieg invasion of Poland, enabling infantry to carry fighting deep into enemy territory. Armies were transported great distances and used in vast airborne (paratroop) operations, the first of which was the German conquest of Crete, and the largest of which was the landing of three Allied paratroop divisions behind German lines to capture bridges across the River Rhine.

The Allied landings in Normandy in June 1944 was the largest amphibious invasion in history. The setting up of extensive supply and service networks providing ammunition, food, and other supplies to armies marked the rapid development of modern military industrial production and engineering.

The importance of guerrilla warfare was demonstrated on many fronts during World War II. The subsequent spread of nationalistic or ideological “brushfire” wars further promoted the use of guerrilla tactics and strategy. Mountain warfare was employed on a wide front between Italy and Austria-Hungary in World War I, involving specially trained alpine troops using skis. In World War II the Germans used mountain divisions in their campaign in Norway, and Soviet troops trained in winter warfare played a vital role during that war, which, after a seemingly endless struggle, reversed its course.

Although nuclear weapons changed the nature of warfare, their value on the battlefield was at first held in doubt. By the 1960s short-range missiles and nuclear cannons had been developed that could be used against troops and supply targets. Efforts to make armies less vulnerable to nuclear attacks turned them into small, highly mobile battlefield forces. Only conventional weapons and tactics have been used in battles of the nuclear age, such as the Vietnam War, as a means of combating guerrilla forces.

Technical demands made of individual soldiers nowadays must often require that a small elite of well-trained volunteers exists to operate under conditions of peace or limited war. This corps tends to be reinforced by large numbers of conscripted soldiers performing traditional functions during large-scale operations. Women are increasingly assigned to infantry, cavalry, armoured, and engineering units in the field, and the technical skills of the military are increasingly used in meeting civilian needs for disaster relief, civic action in war-torn nations, and nation-building projects.