be used against unarmored targets. The larger caliber, shorter range artillery mounting did not go away however. Tanks intended specifically for infantry support (the infantry tanks), expected to take out emplacements and infantry concentrations, carried large calibre weapons to fire large high-explosive shells—though these could be quite effective against other vehicles at close ranges. In some designs – for example, M3 Lee, Churchill, Char B1 – the larger bore weapons were mounted within the tank hull while a second gun for use against tanks was fitted in a turret. However, other strategists saw new roles for tanks in war, and wanted more specifically developed guns tailored to these missions. The ability to destroy enemy tanks was foremost on their minds. To this end, the emerging anti-tank gun designs were modified to fit tanks. These weapons fired smaller shells, but at higher velocities with higher accuracy, improving their performance against armor. Such light guns as the QF 2-pounder (40 mm) and 37 mm equipped British cruiser tanks and infantry tanks in the late 1930s. These weapons lacked a good high-explosive shell for attacking infantry and fortifications, but were effective against the light armor of the time. World War II saw a leapfrog growth in all areas of military technology. Battlefield experience led to increasingly powerful weapons being adopted. Guns with calibres from 20 mm to 40 mm soon gave way to 50 mm, 75 mm, 85 mm, 88 mm, 90 mm, and 122 mm calibre. In 1939, the standard German panzer had either a 20 mm or 37 mm medium-velocity weapon, but by 1945 long-barrelled 75 mm and 88 mm high-velocity guns were common. The Soviets introduced their 122 mm in a turreted heavy tank series, the IS tanks. Shells were improved to provide better penetration with harder materials and scientific shaping. All of these meant improvements in accuracy and range, although the average tank had to grow as well to carry the ammunition, mounting, and protection for these powerful guns. While high velocity tank guns were effective against other tanks, for the most part British tanks moved to a dual purpose 75 mm gun capable of firing a useful HE shell; later in the war adding 76 mm 17pdr gun armed tanks for better antitank capability. Many nations devised "tank destroyers" during the war – a vehicle specifically designed for anti-tank work, and armed more heavily than a tank on