The T18 Howitzer Motor Carriage, abbreviated as HMC. was an American

self-propelled gun Self-propelled artillery (also called locomotive artillery) is artillery equipped with its own propulsion system to move toward its firing position. Within the terminology are the self-propelled gun, self-propelled howitzer, self-propelled m ...

. Its development started in September 1941 as a close-support vehicle using the

M3 Stuart The M3 Stuart/Light Tank M3, was an American light tank of World War II. An improved version of the tank entered service as the M5 in 1942 to be supplied to British and other Commonwealth forces under lend-lease prior to the entry of the U.S. i ...

's chassis. A 75 mm howitzer was mounted on the right front of the vehicle. The gun mount was adapted from the

M3 Grant The M3 Lee, officially Medium Tank, M3, was an American medium tank used during World War II. The turret was produced in two forms, one for US needs and one modified to British requirements to place the radio next to the commander. In British Co ...

. Two prototypes were produced by Firestone and then sent to the

Aberdeen Proving Ground Aberdeen Proving Ground (APG) (sometimes erroneously called Aberdeen Proving ''Grounds'') is a U.S. Army facility located adjacent to Aberdeen, Harford County, Maryland, United States. More than 7,500 civilians and 5,000 military personnel work ...

.Hunnicutt (1992), p. 320-21. Quote: "After inspection of the mock-up, Firestone was authorized to proceed with the construction of the two pilot vehicles." However, they were unsatisfactory because of their high superstructure and nose weight. Because the Army disliked the high superstructure and nearly vertical armor, the T18 was abandoned in 1942, and soon started a new turreted project, the T41 75 mm HMC, also known as the

Howitzer Motor Carriage M8 The 75 mm Howitzer Motor Carriage M8 was a self-propelled howitzer vehicle of the United States in use during World War II. It was developed on the chassis of the M5 Stuart tank and was equipped with a M116 howitzer in an M7 mount. Developm ...

.Chamberlain & Ellis (1969), p. 90.Zaloga (1999), p. 19. Later, the prototypes were kept on display in the Aberdeen Proving Ground until they were destroyed in 1947.

Development

The development started in September 1941 with a requirement for a close-support vehicle based upon the

's chassis, but it was made of a mild steel superstructure. A 75 mm Pack Howitzer was mounted on the right of the glacis plate of the vehicle. The gun mount was modeled from the

M3 Lee The M3 Lee, officially Medium Tank, M3, was an American medium tank used during World War II. The turret was produced in two forms, one for US needs and one modified to British requirements to place the radio next to the commander. In British Co ...

's 75 mm gun's mount. Two prototypes were produced and sent to

s. They were unsatisfactory because of their heavy nose weight. By the time the first pilot model was midway into being completed, the project was canceled since the army disliked the high superstructure, nose weight, and nearly vertical armor. The project was soon superseded by the T41 project. Later, the prototypes were kept on display in the Aberdeen Proving Ground until they were destroyed in 1947.

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* * * {{WWIIAmericanAFVs Self-propelled artillery of the United States World War II armored fighting vehicles of the United States