The 105mm Howitzer Motor Carriage M7 was an American self-propelled artillery vehicle produced during World War II. It was given the official nickname Priest in British service, due to the pulpit-like machine gun ring and following on from the Bishop self propelled gun, the full designation when in British service was 105mm SP Gun, Priest. This developed into a tradition of naming self-propelled guns after ecclesiastic titles with the Sexton and Abbot.
Witnessing the events of the war, American observers realized that they would need a self-propelled artillery vehicle with sufficient firepower to support infantry operations. Lessons learned with half-tracks (such as the T19) also showed that this vehicle would have to be armored and fully tracked. It was decided to use the M3 Lee chassis as the basis for this new vehicle, which was designated T32.
After reworking the M3 by providing an open topped superstructure, mounting a 105 mm howitzer and, following trials, adding a machine gun; the T32 was accepted for service as the M7 in February 1942 and production began that April.
While the first M7s were produced for the U.S. Army, supply was soon diverted to support the Lend-Lease program. Ninety M7s were sent to the British 8th Army stationed in North Africa, who were also the first to use it in combat during the Second Battle of El Alamein. The M7 soon proved itself successful and the British requested 5,500 of them, an order which was never fully completed.
They did find problems with the M7 though, as the primary armaments were of American, not British standard. This meant that the M7s had to be supplied separately, causing logistical complications. It was a problem that was only truly resolved in 1944 on arrival of the 25-pounder-armed Sexton. Until that time though, the British continued to use the M7 throughout the North African Campaign, the Italian Campaign and even a few during the early days of the Normandy Invasion. After the Sexton appeared, most British M7s were converted into "Kangaroo" armored personnel carriers.
In U.S. service the M7 was a great success. Each U.S. armored division had three battalions of M7s, giving them unparalleled mobile artillery support.
A total of 3,490 M7s were built and they proved to be reliable weapons, continuing to see service in the U.S. and allied armies well past World War II.
The first M7s produced were modified M3 Lee medium tanks. In order to maintain a low silhouette, the howitzer elevation had to be restricted to 35°. In May 1942, after only a month of production, the vehicle was altered to increase its ammunition stowage from 24 to 69 rounds. This was achieved by placing seven rounds on the left wall, five on the right, and storing the remainder under floor plates. The M7 also went through a fairly rapid shift from being based on the M3, to having more commonality with the M4 Sherman. The first major example was an adoption of the M4's three piece housing, single piece casting and suspension. In British service, some M7s carried a radio set, which took the place of 24 rounds of ammunition.
Completing the shift, the M7B1 was fully based on the M4A3 Sherman chassis. It was standardized in September 1943, and declared substitute standard in January 1945.
During the Korean War, the limited elevation of the howitzer became noticeably problematic and it was increased to 65°. The machine gun mount also had to be raised to give a 360° firing arc. This was mostly due to the uneven terrain of the Korean conflict. The North Koreans deploying their artillery pieces on higher ground in the mountains north of Seoul and elsewhere.
As one part of the Allied effort to capture Caen and breakout from the Normandy beaches, several M7s had their main gun removed in the field for use as armored personnel carriers and were used in Operation Goodwood. These field modified vehicles were referred to as "Defrocked Priests."
A Canadian armoured personnel carrier (APC) conversion of the M7 for use by British and Commonwealth units in northern Europe. The Kangaroo could carry 20 infantry plus a crew of two. 102 were converted between October 1944 and April 1945. The name "Kangaroo" became generic for all APC conversions of armoured fighting vehicles no longer suitable for combat, including Ram conversions.