50/57, firing shells with an even lower velocity than the Mecar or DEFA guns. Apart from the T-12, which used APDS rounds, these weapons could only use HEAT shells for armor-piercing purposes. France did introduce an APFSDS shell for the DEFA D921 at some point in the 1980s. The last country known to have produced a dedicated anti-tank gun was the People's Republic of China in 1988. The Chinese gun was known as the Norinco Type 86 and was probably manufactured as a replacement for the aging Soviet-sourced T-12. Anti-tank guns continued to be used in a number of conflicts around the world, such as the Six-Day War and the South African Border War. Soviet anti-tank guns in particular were exported to at least 18 other countries after being retired from service, and have continued to see action. Self-propelled anti-tank guns Although still being drawn by horses or towed by trucks, towed anti-tank guns were initially much lighter and more portable than field guns, making them well-suited to infantry maneuvers. As their size and caliber increased, though, the guns likewise became increasingly heavy and cumbersome, restricting their role to static defense. In consequence, during World War II, both sides were compelled to make anti-tank guns self-propelled, which greatly increased their mobility. The first self-propelled anti-tank guns were merely belated attempts to make use of obsolete tanks, such as the Panzerjäger I, which was a Czech 4.7-cm Pak (t) gun mated to a Panzer I chassis. and were used in the Battle of France The trend continued with older tanks and captured vehicles, which were available in large numbers for conversions to self-propelled guns when they were replaced by heavier and better-armed (and armored) tanks. Although just a makeshift solution, these initial experiments proved so successful, they spawned an entire class of new vehicles: dedicated tank destroyers. The US Army's early self-propelled anti-tank guns were 75mm on M2 half-tracks (entering service in 1941) to complement towed artillery and M6 Gun Motor Carriage a 37mm on 4-wheel drive Dodge truck (1942). US Tank Destroyer doctrine emphasised mobility to place the tank destroyers into positions to ambush tank attacks. Tank destroyers offered some advantages over towed anti-tank guns, since a static gun emplacement sacrificed concealment and surprise after firing the first shot, but the same gun mounted on a tracked or wheeled chassis could open fire and throw a tank formation into substantial