M3 halftrack

Carrier, Personnel Half-track M3
An M3 half-track at Fort Knox.
Type	Half-track armored personnel carrier
Place of origin	United States
Service history
Wars	World War II Korean War Suez Crisis Six Day War Lebanese Civil War
Production history
Manufacturer	Autocar Diamond T White Motor Company
Specifications (M3)
Weight	20,000 lb (9.07 metric tons)
Length	20 ft 2 5/8 in (6.17 m) with roller
Width	6 ft 5 1/4 in (1.96 m)
Height	7 ft 5 in (2.26 m)
Crew	1
Passengers	12
Armor	0.25-0.50 in (6-12 mm)
Engine	White 160AX 147 hp (110 kW) at 3,000 rpm
Power/weight	16.2 hp/metric ton
Transmission	Spicer 3461 constant mesh
Suspension	Front: semi-elliptic longitudinal leaf spring Rear: Vertical volute spring
Fuel capacity	60 US gallons (230 litres)
Operational range	200 mi (320 km)
Speed	45 mph (72 kph) on road
Steering system	Steering wheel

The M3 Half-track, known officially as the Carrier, Personnel Half-track M3, was an American armored personnel carrier half-track widely used by the Allies during World War II and in the Cold War. Derived from the M2 Half Track Car, the slightly longer M3 was extensively produced, with about 15,000 units and more than 50,000 derivative variants manufactured (most of which were interim designs).

The design was based on the Citroen-Kégresse half-track. The developers attempted to use as many commercial parts as possible. There were also several dozen variants for different purposes. The M3 and its variants were supplied to the U.S. Army and Marines, as well as British Commonwealth and Soviet Red Army forces, serving on all major fronts throughout the war. Although at first unpopular, it was used by most of the Allies at some point in the war.

Racks under the seats were used for ammunition and rations; additional racks behind the seat backs held the squad's rifles and other stowage. A small rack for mines was added on the outside of the hull just above the tracks. In combat, most units found it necessary to stow additional food, rucksacks and other crew stowage on the outside of the vehicle. Luggage racks were often added in the field, and very late vehicles had rear-mounted racks for this crew stowage.

Early vehicles had a pintle mount, just behind the front seats, that mounted a .50-caliber (12.7 mm) M2 Browning machine gun. The later M3A1 adopted a raised, armored 'pulpit mount' for the .50-caliber, and .30-caliber (7.62 mm) machine guns could be used from mounts along the sides of the passenger compartment. Many M3s were later modified to the M3A1 standard. The body was armored all around, with an adjustable armored shutter for the engine's radiator and a bulletproof windscreen.

Between the world wars, the U.S. Army sought to improve the tactical mobility of its forces. With the goal of finding a high-mobility infantry vehicle, the Ordnance Department had evaluated the half-track design by testing French Citroën-Kégresse vehicles. The White Motor Company produced a prototype halftrack using their own chassis and the body of the M3 Scout Car.