M3 Gun Motor Carriage

The 75 mm Gun Motor Carriage M3 was a United States tank destroyer and self-propelled artillery piece of World War II. It was the most numerous tank destroyer in United States Army service during the critical battles in North Africa and the Philippines; and continued to be used in more limited numbers in Sicily, before being declared obsolete in early 1944. The GMC M3 was then used by the regimental weapons companies of Marine regiments in 1944–1945 at Saipan, Peleliu and Okinawa.

Development
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. In June 1941, an M3 Half-track was mated with a 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 M3s 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. The GMC M3A1 was a variant that used a different gun mount. The 75 mm GMC M3 was reclassified first as limited standard and later, in 1944, as obsolete.

Description
The 75 mm GMC M3 was an M3 Halftrack with an M1897A4 75 mm gun mounted in the rear of the halftrack. The gun had an indirect fire range of 9200 yd, and fired the AP M72 (Armor Piercing) shell that could penetrate 3.2 in of armor at 500 yd, the APC M61 (Armor Piercing Capped) shell that could penetrate 2.8 in of armor at 500 yd, and the HE M48 (High Explosive) shell for use against infantry and other non-armored targets. The GMC M3 carried 59 rounds of 75 mm ammunition on board. The crewmen were equipped with a rifle and four carbines for self-defense.

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.

Allied use
Around 170 GMC M3s were provided to the British Army in early 1943. The British deployed them in the headquarters troops of armored car and tank units as self-propelled artillery pieces. These, known as 75 mm SP, Autocar in British nomenclature, were employed in Tunisia and Italy. The 75 mm GMC M3 was also used by the French Army on a limited basis on the Western Front 1944-45. The M3 GMC was also used by the Philippine Army and Philippine Constabulary during World War II under Japanese Occupation (1942-1945) and the post war era (1945-1960s) using Hukbalahap Rebellion by local government forces against Huk rebels and Korean War by PEFTOK.

Notes and references

 * Notes


 * Bibliography