The half-track military vehicle achieved considerable stardom during World War 2 (1939-1945) though the concept of combining a truck and tracked vehicle was born some decades before. For the United States, three major producers emerged during the wartime period led by the White Motor Company to be joined by Auto Car and Diamond T. In all, about 43,000 half-track vehicles were produced with many joining the ranks of Lend-Lease including 5,000 examples sent to the Soviet Union.
The M9 Half-Track was a development of the classic M2 series produced by the White Motor Company from 1940 onward. International Harvester (IH) provided its equivalent in the M9 for Lend-Lease to American allies and manufacture of this design began in August of 1942 utilizing the same chassis and body as another IH product, the Lend-Lease-minded M5 Half-Track. Total production yielded over 3,400 vehicles in two major guises - M9 and M9A1. One source accounts for 2,026 M9s being completed along with 1,407 of the M9A1 version though another source claims that no M9 models were actually manufactured and the entire stock was comprised of M9A1s. It is known that half of those delivered had powered winches installed at their bows and the remaining stock were completed with simple anti-ditch rollers.
The end-product looked very much the part of the American half-track with its truck-like forward section (including the protected driver's cab) and tank-like rear section showcasing the track-and-wheel system. The rear of the vehicle was open-topped utilizing thinly-armored side walls offering only basic protection against small arms fire. The cargo area could haul nearly all manner of cargo as well as combat-ready infantry. Some forms even mounted armament. The vehicle was typically defended through a single 12.7mm heavy machine gun while up to 2 x 7.62mm machine guns (or equivalent) could be added on pintle mounts depending on operator requirements. Power came from an IHC RED-450-B series gasoline engine of 141 horsepower offering speeds up to 42 miles per hour on paved roads. The wheels at front were suspended in the usual vehicular sense while the rear-mounted tracked units featured single bogie Vertical Volute Spring (VVS) arrangements. Dimensions of the vehicle included a length of 20.6 feet, a width of 7.2 feet and a height of 7.4 feet. The standard operating crew was usually three with seating for ten in the rear section. Weight was in the 9.3 (short) ton range.
The M9 was used throughout World War 2 as it was operated by both the United States and Soviet Union (413) examples as well as Canada and Britain. Other operators became Brazil, China, Czechoslovakia, France, Israel, Japan, Pakistan, and Poland - which meant that examples were still being featured in post-war conflicts such as the Arab-Israeli War (1948), the Korean War (1950-1953), and the Vietnam War (1955-1975). The Israelis operated M9s throughout the Six Day War (1967) and the Yom Kippur War (1973) for their part in its history.
Eventually the days of the half-track became numbered as fighting forces moved away from their design to better protected, all-tracked armored vehicles.