Halftrack vehicles, with a conventional wheeled front axle and a track assembly under the rear section of the vehicle, were produced in large numbers during World War II. The typical design was armored but with an open top. In its various models the halftrack became the utility vehicle of the Armored Force for the duration of World War II and found uses throughout the U.S. military. It served as personnel carrier, reconnaissance vehicle, radio vehicle, ambulance, 81mm mortar carriage, prime mover for antitank guns, the first tank destroyer gun mount, and as an anti-aircraft automatic weapons mount. Despite the multiplicity of its uses, the halftrack was never a fully satisfactory vehicle. Its cross-country mobility was limited, its armor was inadequate, and it afforded no overhead protection. But it was rugged and dependable and except for minor modifications continued to the end of WW II as the most widely used armored vehicle.
Halftracks were a good compromise between the greater security and mobility of tracked armored vehicles and the lighter weight of soft-skin wheeled trucks, but they were ultimately found to be too vulnerable to air attacks and artillery. Although existing inventories of halftracks were still used by the U.S. military in Korea and even Vietnam, the fully tracked and enclosed Armored Personnel Carrier completely replaced the halftrack.
A halftrack moves through a simulated battle during training, Mitchel Field, Long Island, NY, 1943.
In the 1920s, well before World War II, the idea of military halftrack vehicles was studied in European countries and the United States. A number of designs and test vehicles were evaluated in the US, but no action was taken. In 1931, the US Army purchased a French Citroen-Kegresse P17 halftrack for study at Aberdeen Proving Ground, MD. Good test results led to several prototype designs and test vehicles in the 1930s, intended for use as prime movers or personnel carriers.
Halftrack Scout Car, T14, 1940.
The direct ancestor of all US halftracks was the halftrack personnel carrier T7, created at Rock Island Arsenal in 1938 (working with White Motor Co.) from an M2A1 wheeled Scout Car by replacing the rear axle with a track assembly. (M2 Scout Car was later renamed M3A1 Scout Car) Testing of the underpowered T7 provided valuable information that led to a follow-on test vehicle designated T14, built by White Motor Co. with the more powerful 160AX engine, delivered to Aberdeen Proving Ground in May 1940. The modified T14, incorporating the experience of further tests, was standardized as the M2 Halftrack, to be manufactured by White, Autocar, and Diamond T. The first standard M2 halftrack production vehicles were delivered to the US Army in May 1941.
The M3 Halftrack was based on the M2, with a ten-inch longer body and other changes in layout to accomodate an infantry squad. The larger M3 became the platform for the many halftrack variants produced during WW II while the M2 was gradually phased out. Nonetheless, incremental improvements developed from combat experience were incorporated into both M2 and M3 vehicles as new production or retrofit. In 1943, a machine gun ring mount replaced the machine-gun skate rail (on the M2) and post mount (on the M3) at which point the halftracks were redesignated as M2A1 and M3A1.
In December 1942, International Harvester Co. started producing halftracks of a modified design. Small changes were authorized to simplify manufacturing, and the revised vehicles were designated as M9 (similar to the M2) and M5 (similar to the M3). The main differences were an IH engine, flat fenders, and a hull with rounded corners.
Chart of Military Halftracks
In this chart of military halftracks, click on the photo link to go to the page of photos and information for the specific vehicle. See also APCs and Self-Propelled Artillery.
M3 Gun Motor Carriage (GMC) with 75mm Field Gun, known as T-12 pre-standardization