During the early stages of World War II, US Army observers realized that they would need a self-propelled artillery vehicle with sufficient firepower to support armored operations. Lessons learned with half-tracks also showed that this vehicle would have to be armored and fully tracked. It was decided to use the M3 Leechassis as the basis for this new vehicle design, named T32. The pilot vehicles used the M3 chassis with an open-topped superstructure, mounting an M1A2 105 mm howitzer, with a machine-gun added after trials. The T32 was accepted for service as the M7 in February 1942 and production began that April. The British Tank Mission had requested 2,500 to be delivered by the end of 1942 and a further 3,000 by the end of 1943, an order which was never fully completed. As the M4 Sherman tank replaced the M3, it was decided to continue production using the M4 chassis. The M7 was subsequently supplanted by the M37 HMC.
Operational history
A total of 3,489 M7s and 826 M7B1s were built. They proved to be reliable weapons, continuing to see front-line service in the US and other armies well past the end of World War II.
North Africa
During the North African campaign, 90 M7s were received by the Eighth Army in North Africa, which was also the first to use it, during the Second Battle of El Alamein, alongside the Bishop, a self-propelled gun based on the 87.6 mm calibre Ordnance QF 25-pounder gun-howitzer. The British Commonwealth armies had logistical problems in supplying the M7, as it used US ammunition that was not compatible with standard British artillery pieces or tank guns, and had to be supplied separately. Whereas the Sexton – a rival self-propelled gun developed in Canada featured the standard British QF 25-pounder. Despite supply problems, British Commonwealth forces used the M7 throughout the campaigns in North Africa and Italy.
North-West Europe
During the invasion of Normandy, from June 1944, the artillery regiments of the British 3rd and 50th divisions, and the Canadian 3rd Division were equipped with the M7; however, these were replaced by towed 25-pounder guns in early August. as it moves into position to support an attack on Caen, 8 July 1944. During the Battle of the Bulge, each US armored division had three battalions of M7s, giving them unparalleled mobile artillery support.
Korean War M7 Priests remained in use during the Korean War, where their flexibility, compared to towed artillery units, led the US Army on the path to converting fully to self-propelled howitzers. The limited gun elevation of the M7 hampered its ability to shoot over the tall Korean mountains, so 127 M7B1s were modified to permit the full 65 degrees elevation in a model known as the M7B2. After the Korean War, many of these were exported to NATO countries, notably Italy and Germany. Israel Israel acquired a number of M7 Priests during the 1960s and employed them in the Six-Day War, the War of Attrition and the Yom Kippur War. In the last conflict, three M7 units, the 822nd, 827th and 829th Battalions in the IDF Northern Command, supported the occupation of the Golan Heights. West Germany The new West German Bundeswehr received 127 Priests as its first self-propelled artillery vehicle. They entered service in 1956 and were used until the early 1960s.
A British self-propelled gun armed with the Ordnance QF 25-pounder in design from 1941 was nicknamed Bishop as its appearance was said to resemble a bishop's mitre and a replacement, the US 105 mm Howitzer Motor Carriage M7, was called "Priest", as part of its superstructure was said to resemble a pulpit. Following this line of names, a 1942 self-propelled gun armed with the QF 6 pounder was named Deacon and a 1943 weapon carrier with the QF 25-pounder was called Sexton.
