The M9 half-track was a half-track produced by International Harvester in the United States during World War II for lend-lease supply to the Allies. It had the same body and chassis as the M5 half-track (also built by International Harvester for lend-lease). The M9 served for a significant amount of time. Three thousand five-hundred were produced by the end of World War II.
The United States adopted half-tracks in large numbers as they could be built more quickly and cheaply by civilian vehicle producers than vehicles from the established armored vehicle manufacturers. The M2 half-track car had first been intended as an artillery tractor, but was also used for carrying the machine gun squads of armored infantry regiments and for reconnaissance units.
In order to supply U.S. allies, much more production was required than was possible through the firms producing the M2 (and the larger M3 half-track). International Harvester (IH) could produce half-tracks, but some differences had to be accepted due to different manufacturing methods and components. This led to IH producing for lend-lease the M5 half-track and M9 as equivalents for the M3 and M2 respectively.
The M9 used the same chassis and mechanical components as the M5. The M9A1 variant of the M9 matched the improvements made to the M2, M3, and M5, changing to ring mount machine gun mount and three pintle machine gun mounts. As with the M5, due to the lack of face-hardened armor, homogenous armor was used. Although thicker, it gave less protection and could be penetrated by armor-piercing rifle bullets from 270 m rather than 180 m. The armor also made the vehicle heavier, though the performance was essentially similar. The M9 started production in August 1942, at IH. The M9 and M9A1 were manufactured en masse and 2,026 were produced in total. 2,026 M9s and 1,407 M9A1s were produced in 1943.




















