The M3 Gun Motor Carriage (GMC) was a United States Army tank destroyer equipped with a 75 mm M1897A4 gun, which was built by the Autocar Company during World War II. After observing the new and often decisive, uses of armored vehicles on both sides during the French campaign of 1940, the US Army decided that it required a 75 mm self-propelled gun, based on the chassis of the M3 Half-track. This was initially known as the T12. However, after the addition of features such as the gun shield from the M2A3 (a carriage for the M1897A4), the new vehicle entered production under the name M3 Gun Motor Carriage (or M3 GMC). Because the number of M2A3 gun shields available was insufficient for the M3 GMC order, a new gun shield was designed. Variants featuring the new shield were designated M3A1 GMC.