the 75 mm main gun, which was a vast improvement over the 37 mm. The M24's light armor made it vulnerable to enemy tanks, anti-tank guns, and hand-held anti-tank weapons. In the Korean Conflict, M24s were the initial U.S. tanks directed to combat the North Korean T-34-85s. The occupation troops in Japan from which the tanks were drawn were inexperienced and under-equipped due to rapid demobilization after World War II. The M24 fared poorly against these better armed, better armored, and better crewed medium tanks, losing most of their number while inflicting only minor damage on the T-34 units. Managing a fighting withdrawal, they ended up as artillery in the Pusan Perimeter; in August reinforcements from the US and the Commonwealth brought heavier tanks that could easily dispatch the T-34s. M24s were more successful later in the war in their reconnaissance role, supported by heavier, more capable tanks such as the M4 Sherman, M26 Pershing, and M46 Patton. M41 Walker Bulldog The development of the T37 began in 1947 to replace the M24 Chaffee. The vehicle was designed to be air-transportable, and with heavier firepower, provided by an advanced 76 mm gun. In 1949, with the adoption of a less ambitious rangefinder, the project's designation was changed to M41. Production started in 1951 at Cadillac's Cleveland Tank Plant, and by 1953 the new tank completely replaced the M24 in the United States Army. It was later designated the M41 Walker Bulldog. The M41 was agile and well armed. On the other hand, it was noisy, fuel-hungry and heavy enough to cause problems with air transport. The Walker Bulldog saw limited combat with the U.S. Army during the Korean Conflict, but for the most part, the conflict served as a testing ground to work out the tank's deficiencies, especially with its rangefinder. At the time, it was designated as the T-41, and was rushed to the battlefield even before its first test run. This was due to the fact that the North Koreans were supplied with Soviet T-34 tanks, which were superior to the M24. It also was used in nearby Japan: by 1961, 150 were delivered to the Japan Ground Self-Defense Force to supplement their Type 61 medium tanks. It was also used in the Bay of Pigs conflict by the Brigade 2506, with the M41 Walker Bulldog tanks going against the Cuban T-34-85 tanks, with five T-34-85 tanks destroyed