The M36 tank destroyer, formally 90 mm Gun Motor Carriage, M36, was an American tank destroyer used during World War II. The M36 combined the hull of the M10 tank destroyer, which used the M4 Sherman's reliable chassis and drivetrain combined with sloped armor, and a new turret mounting the 90 mm gun M3. Conceived in 1943, the M36 first served in combat in Europe in October 1944, where it partially replaced the M10 tank destroyer. It also saw use in the Korean War, where it was able to defeat any of the Soviet tanks used in that conflict. Some were supplied to South Korea as part of the Military Assistance Program and served for years, as did re-engined examples found in Yugoslavia, which operated into the 1990s. Two remained in service with the Republic of China Army at least until 2001. The vehicle is also known under the unofficial nickname Jackson, but this designation appears to be a postwar appellation that was never used by the US Army. Doctrine U.S. combined arms doctrine on the eve of World War II held that tanks should be designed to fulfill the role of forcing a breakthrough into enemy rear areas. Separate GHQ tank battalions would support infantry in destroying fixed enemy defenses, and armored divisions would then exploit the breakthrough to rush into the enemy's vulnerable rear areas. U.S. tanks were expected to fight any hostile tanks they encountered in their attack, but the mission of defeating massed enemy armored counterattacks was assigned to a new branch, the Tank Destroyer Force. Tank destroyer units were meant to counter German blitzkrieg tactics. Tank destroyer units were to be held as a reserve at the corps or army level, and were to move quickly to the site of any massed enemy tank breakthrough, maneuvering aggressively and using ambush tactics (charging or chasing enemy tanks was explicitly prohibited) to destroy enemy tanks. This led to a requirement for fast, well-armed vehicles. Though equipped with turrets (unlike most self-propelled anti-tank guns of the day), the typical American design was more heavily gunned, but more lightly armored, and thus more maneuverable, than a contemporary tank. The idea was to use speed and agility to bring a powerful self-propelled anti-tank gun into action against enemy tanks. Design With the advent of heavy German tanks such as the Panther and Tiger, the standard U.S. tank destroyer, the M10