M3 Gun Motor Carriage - American Use

American Use

Confronted with an impending war with Japan, 75 GMC M3s and T12s, termed "Self-Propelled Mount" (SPM) halftracks, were shipped to the Philippine Islands in September 1941 to form the (2nd) Provisional SPM Brigade. These vehicles saw action during the Japanese invasion of the Philippines, and some were later captured by the Japanese and used against U.S. forces in 1944.

The GMC M3 was the most widely deployed tank destroyer in U.S. tank destroyer battalions during the campaign in Tunisia in late 1942 and early 1943, and was prominent during the battles of Sidi Bou Zid, Kasserine Pass, and El Guettar. Although many GMC M3s were lost in these battles, the U.S. Army concluded that improper employment had caused some of these losses. The GMC M3 was again used in the tank destroyer role in the Sicilian Campaign in July 1943. Subsequently, the GMC M3 was phased out of tank destroyer battalions and replaced by the GMC M10, a turreted tank destroyer mounting a modern 3 inch gun. Small numbers were used for specialised tasks, such as assault guns with the Rangers of Task Force Sugar in Brittany.

Although then considered obsolete for use against German tanks, the GMC M3 was powerful enough to destroy the light tanks deployed by the Japanese, and so the GMC M3 continued to be used in the Pacific Theater, primarily with regimental weapons companies of the United States Marine Corps, seeing action on Saipan, Peleliu, and Okinawa, among other island battles. Because tanks were not frequently deployed by the Japanese, the GMC M3 was often used as a self-propelled artillery piece or for direct fire support against Japanese fortifications. In 1945, the GMC M3 was replaced in Marine Corps use by the 105 mm HMC M7 self-propelled artillery piece.