The M7 105mm Howitzer Motor Carriage 'Priest' was a self-propelled gun that entered combat in North Africa late in 1942 and that served with the British and American armies from then until the end of the war, fighting on Sicily, in Italy, in Normandy and north-western Europe and in smaller numbers in the Pacific.
Work on the basic design of the M7 began in June 1941 when studies for the T32 Gun Motor Carriage were authorised. This vehicle would carry a 105mm howitzer on the chassis of a M3 medium tank, with a new open topped superstructure.
In October 1941 General Jacob L. Devers, Chief of the Armored Force, recommended that two T32 pilots should be manufactured, and in November they were authorized. The Baldwin Locomotive Works completed the two pilots in about a month and they were then sent to the Aberdeen Proving Ground for tests.
The first pilot then went to the Armored Force Board at Fort Knox for further tests, which began on 5 February 1942. The armoured board accepted the basic design but asked for a few changes. The gun mount needed to be rotated to the right to give it the full 45 degrees of traverse - the original position had restricted it to 31 degrees. An anti-aircraft gun was requested, as was an access door over the transmission, more ammo storage and seats for the gun crew. The second pilot, which was still at Aberdeen, was modified to comply with these requests. At this stage the anti-aircraft 'pulpit' that gave the vehicle its nickname was added at the front-right.
In February 1942 production of 600 T32s was authorized. The modified second pilot was sent to the American Locomotive Company, where production got underway. In April the T32 was standardised as the M7 105mm Howizter Motor Carriage, and in the same month the first production vehicles were completed.
The M7 was known as the 105mm, SP, 'Priest', in British service. Britain originally asked for 5,500 M7s - 2,500 to be delivered by the end of 1942 and the remaining 3,000 during 1943. This was actually more M7s than were ever produced, but a large number did enter British service. They entered combat at the second battle of El Alamein and were used during the rest of the campaign in North Africa, for the entire Italian and at the start of the Normandy campaign. They were soon withdrawn from use in Normandy and replaced with the Sexton.
The M7 entered American service in November 1942, taking part in Operation Torch. It replaced the T19 105mm Howitzer Motor Carriage (based on a half-track), which had been adopted as a temporary expedient.
The M7 was based on the standard M3 Lee medium tank chassis, with the Wright Continental engine and the rear and drive at the front. The normal superstructure and turret of the M3 was removed and a new open topped fighting compartment was installed. This took up the middle third of the vehicle, in the space between the final drive and the engine. A tarpaulin cover was provided to protect the fighting compartment against wet weather.
The M7 was armed with a M2A1 105mm Howitzer, mounted slightly to the right of the centre. It could traverse 15 degrees to the left and 30 degrees to the right, and had a range of elevation from -5 to +35 degrees. The gun fired HE, HEAT, white phosphorous and smoke shells, with a maximum range of 11,400 yards/ 10,424 meters and a rate of fire of eight rounds per minute. Early production examples could carry 57 shells while later vehicles carried 69.
The M7's nickname of 'Priest' is said to have been given to it by British troops in North Africa who thought the anti-aircraft gun mount looked like a pulpit. The gun was mounted at the front-right of the fighting compartment, and was protected by a curved sheet of armour that formed three-quarters of a circle (with the last quarter open into the fighting compartment). A gun ring was carried on top of this pulpit, which bulged out to the right of the main compartment and did stick out.
The driver sat to the left of the gun. He had a large viewing hatch that could be opened in safer circumstances, or a viewing scope that could be used when the hatch was closed.
The M7 was based on the M3 medium tank and had the same three piece bolted nose. The M7B1 was based on the M4A3 Sherman, and had a single piece cast nose.
The M7 was powered by a Wright Continental radial engine, the M7B1 was a Ford GAA V8 petrol engine.
Both versions used vertical volute suspension, with three bogies on each side, each carrying two road wheels.
American Locomotive produced 2,814 of the original M7 - 2,028 in 1942 and 786 in 1943. They also produced 500 improved M7s with the extended side armour during 1944, for a total of 3,314 vehicles.
The Federal Machine and Welder Company produced anther 176 M7s.
The Pressed Steel Car Company produced 826 M7s and M7B1s between March 1944 and February 1945. Most of these vehicles were M7B1s - at least 70% of the 644 produced in 1944 and all of the 1945 production.
During the Korean War 127 M2B1s were converted to the M7B2 (see variants for details).
Ninety M7s reached the Eighth Army in September 1942 and the vehicle made its combat debut during the Second Battle of El Alamein. The 'Priest' replaced the earlier 'Bishop' self propelled gun in the Eighth Army, and remained in service during the pursuit of Rommel after El Alamein, the fighting in Tunisia, the invasion of Sicily and the entire Italian campaign. In British service it was normally used in field artillery regiments.
The Priest was also used by the 21st Army Group during the Normandy campaign, but early in the campaign it was replaced with the Sexton self-propelled gun. The spare Priests then had their gun removed to turn them into Kangaroo Armoured Personnel Carriers (or 'defrocked Priests'), and remained in use to the end of the war.
North Africa, Italy and the European Theatre
The M7 became the standard equipment of the artillery battalions that formed part of US armoured divisions, and was used in that role from the end of 1942 until the end of the Second World War. During 1945 the M7 was slowly replaced by the M37 HMC, but the conversion was never completed. It made its American combat debut during Operation Torch. The American Army used the M7 during the invasion of Sicily, the Italian campaign and the invasion of Normandy.
The M7 was also provided to the Free French, who used it during the fighting in northern Europe in 1944-45.
The M7 was used in smaller numbers in the Pacific, where many of the smaller islands were unsuited to its use.
It was used during the invasion of Luzon. Its first major clash with Japanese armour came at San Manuel on 24 January 1945 when the US 161st Infantry, supported by the division's M7s and a company of M4 Shermans attacked a position defended by a number of Japanese Type 97 Shinhoto Chi-ha medium tanks. The M7s were used to destroy the tank revetments being used to protect the Japanese tanks. On the following night the remaining thirty Japanese tanks attacked the American lines but were quickly destroyed. The M7 was also used by the 637th Tank Destroyer Battalion on Luzon.
The M7 was also used on Okinawa, during the final land battle of the Second World War.
After the end of the Second World War the US Army kept some of its M7s and M7B1s, but others were scrapped or sold off. The US Army used the M7 during the Korean War, where it was modified to increase the maximum elevation of the gun.
The Nationalist Chinese on Taiwan received a number of M7s but probably didn't use them in combat.
Pakistan used the M7 during the 1965 and 1971 wars with India.
Israel used the M7 during the Six Day Way of 1967 and the Yom Kippur War of 1973. This was probably the last combat use of the M7.
The M7 was the original production version, based on the M3 Lee Medium tank. Later production vehicles had extra armoured plates added to the hull sides to protect the tip of the stored ammunition from enemy fire.
The M7B1 used the M4A3 Sherman chassis and a Ford V8 engine.
The M7B2 was a modified version of the Priest produced for use during the Korea War. The howitzer was given a taller mount that allowed the elevation to be increased in order to allow it to hit the rear slopes of the steep hills found in the country.
Production: 4, 316
Hull Length: 19ft 9in (M7), 20ft 3 3/4in (M7B1)
Hull Width: 9ft 5 1/4in
Height: 8ft 4in
Crew: 7 (commander, driver, five gun crew)
Weight: 50,634lb (M7), 50,000lb (M7B1)
Engine: Continental R-975 (M7), Ford GAA V8 (M7B1)
Max Speed: 26mph (road), 15mph (cross country)
Max Range: 85-125 miles road radius
Armament: 105mm Howitzer M1A, M2 or M2A1, one .50in anti-aircraft machine gun