Prior to the outbreak of WWII, the U.S. Army Ordnance Department began testing prototype half-track vehicles, including a White Motor Co. design that combined an M3 Scout Car with a White chassis. With armored bodies, an armored radiator shutter and bulletproof glass windscreen, the half-track offered crew protection and endurance under fire, while its speed - up to 45 mph - added a new dimension to infantry mobility. After testing and acceptance, the White design was standardized and during the war built by White, Autocar and Diamond T as the M3 half-track. Nearly 41,000 would be produced during the war, along with an additional 13,500 units of the smaller M2. Variants included the M13, M15 and M16 gun motor carriage, the M21 mortar carrier, and the T19 and T30 Howitzer motor carriages. Created in 1944, this technical manual includes many photos and over 350 pages of text that reveal a great deal about the weapon's design and capabilities. Intended as a manual for those charged with operation and maintenance, this manual shows many aspects of its engine, cooling, power train and other systems. Originally labeled restricted, this manual was declassified long ago and is here reprinted in book form. Care has been taken to preserve the integrity of the text.