An assault gun is a form of self-propelled artillery which utilizes an infantry support gun mounted on a motorized chassis, normally an armored fighting vehicle. Assault guns are designed to provide direct fire support for infantry attacks, especially against other infantry or fortified positions. The term is a literal translation of the German word Sturmgeschütz, which was applied to the first purpose-built assault gun, the StuG III, in 1940. Historically, the concept of assault guns was very similar to that of the infantry tank, as both were combat vehicles intended to accompany infantry formations into battle. However, during World War II assault guns were more mobile than tanks and could be utilized as both direct and indirect fire artillery. Although they could approximate the firepower of a tank, assault guns mostly fired high explosive shells at relatively low velocities, which were well suited for their role of knocking out hard points such as fortified positions and buildings. They were not intended to be deployed as tank substitutes or dedicated tank destroyers. Nevertheless, as the conflict progressed, the increasing proliferation of tanks on the battlefield forced many assault gun units to engage armor in defense of the infantry, and led to armies becoming more dependent on multipurpose designs which combined the traditionally separate roles of an assault gun and a tank destroyer. German and Soviet assault guns introduced during World War II usually carried their main armament in a fully enclosed casemate rather than a gun turret. Although this limited the field of fire and traverse of the armament, it also had the advantage of a reduced silhouette and simplified the manufacturing process. The United States never developed a purpose-built assault gun during the war, although it did modify preexisting armored fighting vehicles for that role, including the M4 Sherman and M5 Stuart tanks and the M3 Half-track. The assault gun concept was largely abandoned during the postwar era in favor of tanks or multipurpose tank destroyers attached to infantry formations which were also capable of providing direct fire support as needed. In the United States and most Western countries, the assault gun ceased to be recognized as a unique niche, with individual examples being classified either as a self-propelled howitzer or a tank. The Soviet Union continued funding development of new assault guns as late as 1967, although few of its postwar designs were adopted in large numbers. In Soviet and other Eastern European armies, the traditional assault gun was primarily superseded by tank destroyers such as the SU-100 capable of supporting either infantry or armor.