Once the United States rearmament program was under way in 1941, the U.S. Army recognized the need to develop full-tracked tractors to tow the various calibers of artillery pieces then entering service. The wheeled trucks in service were too limited in towing and cross-country ability to properly address the U.S. Army’s need for mobility and towing capacity in its new armored divisions. The M5 prototype was tested in late 1941 and entered service in October 1942. The M5 was designed specifically to tow the medium category artillery pieces – specifically the 105-mm and 155-mm field howitzers. The tracks and suspension were based on the M3 “Stuart” light tank. The M5 was designed to carry the complete howitzer crew, their weapons, gear and ammunition (56 rounds of 105-mm and 24 rounds of 155-mm). A winch was mounted on the front, and air brakes were provided for operating the brakes on the towed howitzer. The M5 successfully served the U.S. artillery units throughout World War II on all fronts. The M5 was well-built and well-liked by its crew.