YouTube caption with links added:
The Army’s first motorized tank destroyer, featured here, was the “T12/M3 Gun Motor Carriage,” a modified M-3 half track with a 75mm M1897A4 gun mounted in the rear, an adaptation of the quick firing “French 75.” The idea of such a thinly armored vehicle facing armored tanks may seem insane today . . .
but the Army’s tank destroyer doctrine at the time was “shoot and scoot,” where fast moving anti-tank vehicles would harry the advance of enemy armor, shooting from covered positions, quickly retreating, and and then repeating the process, decimating the enemy.
When they tried to fight toe to toe with German tanks at Kasserine Pass in Tunisia, the results were disastrous, but used as intended, they could be effective against early war Axis tanks. (And let’s face it. This vehicle was clearly a stop gap measure rushed into production.)
M3s were soon replaced with the more effective M10 in Europe, but were used successfully against more lightly armored Japanese forces in the Far East & Pacific Theaters throughout the war, often as mobile artillery. Highlights of the film include field maintenance, firing and maneuvers in the field.
A total of 2,203 were produced, of which 1,361 were converted back into M3A1 half-tracks The film begins with rare footage of Gen. A.D. Bruce opening the brand new tank destroyer training facility at the just completed Camp (later Fort) Hood army base, near Killeen,TX..
Trivia: An M3 mounting a 75mm gun was featured in the classic World War 2 film “Kelly’s Heroes,” starring Clint Eastwood.