The M7 Priest was the most widely used self-propelled gun by the US Army during World War II, becoming the workhorse of armored division artillery batallions which could keep up with the tanks. It was decided early on to mate the 105-mm M2 howitzer on the chassis of the M3 tank, which would provide greater stability and off-road performance compared to earlier designs that were based on the M3 half-track. This ensured the M7 would be sufficiently protected, although the open-top superstructure still left it vulnerable to plunging fire. An M2 Browning machine gun was also added in a prominent gun ring which resembled a church pulpit; this in turn led to it being named Priest by a British purchasing commission. The M2 howitzer was generally seen as reliable and accurate, with its main drawback being its high recoil. Later versions of the M7 were based on the M4 chassis once these were more widely available. The M7 first saw action at El Alamein with the British Army, and were in widespread use by both main Allied armies after D-Day, with each US armoured divisions equipped with no less than three batallions each by late 1944. It was also widely used in the Pacific, mainly in the Burma and South-West Pacific theaters. Post-war it was employed by West Germany and Israel, the latter which used it in its its 1967 and 1973 wars.

The initial T32 was based on the M3 Lee chassis and entered production as the 105 mm Howitzer Motor Carriage, M7 in April 1942. Various improvements to the basic design were made after production began, including increased ammunition and, most importantly, a switch to the M4 Sherman chassis (which strangely, did not warrant a designation change). The M7B1 was the only major wartime variant, and was based on the M4A3 chassis. The M7B2 was developed during the Korean War and featured an increase in gun elevation to 65°, which was similar to the T32 prototype (production versions reduced it significantly). British variants include the so-called \'Defrocked Priest\', which had the gun removed in the field for conversion into an APC as well as the Canadian-built Kangaroo which was a dedicated APC which could carry as many as 20 troops.