T40

T24 Gun motor carriege

The U.S. Army expressed a need for a vehicle capable of stopping and destroying enemy tanks. The new vehicle, dubbed the "Tank Destroyer", would have the same armor protection and general mobility of a standard tank, but would be heavily armed with enough punch to decimate enemy armored formations. Up until 1941, the only vehicles available were modified trucks and half-tracks, which lacked greatly in the mobility, firepower and armor departments.

During the summer of 1941, Baldwin Locomotive Works began development of a vehicle to fill the need for a true tank destroyer. They began with the chassis of an M3 Lee medium tank, added a modified superstructure with an open, hexagonally-shaped top, and armed the vehicle with the M1918 3-inch gun. The Ordnance Department accepted the vehicle for testing at Aberdeen at the end of the summer, designating it the T24 gun motor carriage. However, the extremely high silhouette of the vehicle was thought to detract from its ability to stalk its prey, and gun was found to be lacking in range and accuracy. The T24 was returned to Baldwin for adjustments.

T40/M9 America's First Tank Destroyer

What Baldwin later returned to the Army was basically a somewhat improved T24. Indeed, it was the T24 pilot vehicle, simply modified with a slightly lower superstructure and some minor improvements to the weapon and related systems. The vehicle was accepted for testing at Aberdeen once more, this time under the designation of T40. The Ordnance Department was still far from impressed, but a surprise attack on Pearl Harbor by the Japanese, and the subsequent entry of the United States into the war prompted the vehicle's adoption as the Army's first standardized full-track tank destroyer. It was christened the 3-inch Gun Motor Carriage, M9, and a production contract was awarded for 1,000 examples.