The German victory over France in 1940 using armored divisions profoundly impressed the United States Army. Realizing that defense against tanks was essential, an urgent requirement was issued for the development of tank destroyers for the U.S. Army.[1] In June 1941, an M3 Halftrack was mated with an 75 mm gun M1897A4 , which was an American version of the famous "French 75" of World War I fame. This experimental vehicle was known as the T12, and proved to work remarkably well given the speed with which it was developed. Standardized in October 1941 as the 75 mm GMC M3, over 2,200 75 mm GMC M3's were produced until April 1943. However, a large number of them were converted back to standard halftracks before issue to troop units, resulting in only 842 seeing field service.[2] The GMC M3A1 was a variant that used a different gun mount