M3 GMC

Left: M5A1 Stuart light US tank. Right: 75mm M3 GMC Tank Destroyer. The M5A1 was basically a better armored version of the earlier M3 Stuart, with add'l armor added around the sides of the upper chassis and the turret and an upgraded, Cadillac-produced engine. Armament: M6 37mm main gun, (2) .30 cal. machinegun (coaxial with main gun and at co-driver's position), (1) .50 cal. machinegun (turrert, pintel-mounted). Used primarily for recon and scouting missions. The 75mm GMC M3 was the only anti-tank means the US had at the start of WWII, being pressed quickly into service. It first saw action in North Africa, where it had a limited effect against the German Pzkfw III and IV main battle tanks. A main drawback was the limited side traverse of its gun. Armament: M1897 75mm field gun mounted in M3 halftrack chassis. Eventually replaced by the M10, M18, & M36 Tank Destroyers.

The 75 mm Gun Motor Carriage M3 was a United States tank destroyer and self-propelled artillery piece of the Second World War.


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.

M-3 Tank Destroyer with the 75mm gun, and it's five man crew.

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. The GMC M3A1 was a variant that used a different gun mount. The 75 mm GMC M3 was reclassified first as limited standard and then as obsolete in 1944.

This black and white picture is from a magazine of the era, showing the M-3 Gun Motor Carriage.

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 9,200 yards (8,400 meters), and fired the AP M72 (Armor Piercing) shell that could penetrate 3.2 inches of armor at 500 yards, the APC M61 (Armor Piercing Capped) shell that could penetrate 2.8 inches of armor at 500 yards, and the HE M48 (High Explosive) shell for use against infantry and other non-armored targets. 59 rounds of 75-mm ammunition were carried aboard. The crew were equipped with a rifle and four carbines for self defense.

M3 75mm Gun Motor Carriage, Special Weapons Company, 2nd Marine Division, Tinian, in action on the 30th of July 1944.

American Use

Confronted with an impending war with Japan, 75 GMC M3's and T12's, 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.

Almost invisible in the thick jungle vegetation, an M3 GMC supports Marine operations on Hill 660, Cape Gloucester, New Britain, December 1943 - January 1944. The barrel of the 75mm gun points to the left, just left of center.

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 M3's were lost in these battles, the U.S. Army concluded that improper employment had caused some of these losses.

M3 75mm Gun Motor Carriage halftracks, airbase security, North Africa during WW II.

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. 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 U.S. 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.

M3 75mm Gun Motor Carriage, seen in Italy, 1945. A second vehicle is visible to the right.

Allied use

Around 170 GMC M3's 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 during on the Western Front 1944 - 1945.

75-mm GMC M3.

75 mm Gun Motor Carriage M3

Type Tank destroyer / self-propelled artillery
Place of origin United States

Specifications

Weight 20,000 lb (9.1 metric tons)
Length 6.24 m (20.46 ft)
Width 2.16 m (7.08 ft)
Height 2.44 m (8.02 ft)
Crew 5 (Commander, (3x) gun crew, driver)
Armor 6-16 mm (¼-⅝ in)
Primary armament 75 mm Gun M1897A4
59 rounds
Secondary armament None
Engine White 160AX 142.5 hp (105 kW)
Power/weight 15.71 hp/t
Suspension Semi-Elliptic Volute Spring
Operational
range 320 km (200 mi)
Speed 70 km/h (45 mi/h)

Stylized 75-mm GMC M3 used as insignia for U.S. Tank Destroyer Force soldiers.