World War 2 In Review: American M7 Howitzer Motor Carriage

Left front view of M7 Howitzer Motor Carriage, "Finalist."

The 105 mm Howitzer Motor Carriage M7 was an American self-propelled artillery vehicle produced during World War II. It was given the official service name 105 mm Self Propelled Gun, Priest by the British Army, due to the pulpit-like machine gun ring, and following on from the Bishop and the contemporary Deacon self-propelled guns.

Witnessing the events of the war, U.S. Army observers realized that they would need a self-propelled artillery vehicle with sufficient firepower to support armored operations. Lessons learned with half-tracks (such as the T19 HMC - 105mm Howitzer on M3 Half-track chassis) 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 design, which was designated T32.

The pilot vehicles used the M3 chassis with an open-topped superstructure, mounting an M1A2 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. Before production had begun, 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 M4 chassis was a development of the M3). The M7 was subsequently supplanted by the M37 HMC (on the "Light Combat Team" chassis that also gave the M24 Chaffee light tank). While the first M7s were produced for the U.S. Army, some were diverted to support the British in North Africa. Ninety M7s were sent to the British Eighth Army in North Africa, who were also the first to use it in battle during the Second Battle of El Alamein as well as their own Bishop, a self-propelled gun based on the 87.6 mm caliber Ordnance QF 25-pounder gun-howitzer.

The British did find problems with the M7 though, as the primary armament was of U.S., 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 1943 on arrival of the 25-pounder-armed Sexton developed by the Canadians on a M3 chassis. Until that time though, the British continued to use the M7 throughout the North African Campaign and the Italian Campaign. The three assault infantry divisions (3rd and 50th British, 3rd Canadian) that landed on Sword, Juno and Gold beaches on D-Day during the Normandy Invasion had their artillery regiments equipped with the M7; these were replaced by the standard towed 25-pounder guns of the infantry in early August. It was also used in Burma and played a significant part in the Battle of Meiktila and the advance on Rangoon in 1945. After the Sexton appeared, most British M7s were converted into "Kangaroo" armored personnel carriers.

In U.S. service, the M7 was a great success. During the Battle of the Bulge, each U.S. armored division had three battalions of M7s, giving them unparalleled mobile artillery support.

A total of 3,490 M7s—4,267 if including the M7B2—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.

Type: Self-propelled artillery

Place of origin: United States

Used by:

U.S. Army

Argentine army

Belgian army

British Army

Canadian Army

Israel Defense Forces

Norwegian army

Pakistan Army

Philippine Army

Philippine Constabulary

Taiwanese Army

Manufacturer:

American Locomotive Company (M7)

Pressed Steel Car (M7B1)

Federal Machine and Welder (M7)

Produced: April 1942–July 1945

Number built:

M7: 3489

M7B1: 826

M7B2: 127 converted from M7B1

Weight: 50,640 lb (22.97 metric tons)

Length: 19 ft 9 in (6.02 m)

Width: 9 ft 5 in (2.87 m) with sandshields

Height: 8 ft 4 in (2.54 m); 9 ft 8 in (2.95 m) over AA machine gun

Crew: 8

Armor: 12–62 mm

Main armament: 105 mm M1/M2 Howitzer; 69 rounds

Secondary armament: 1 x 0.5 in (12.7 mm) M2 Browning machine gun; 300 rounds

Engine: Continental R-975 C1/C4; Ford GAA (M7B1); 400 or 340 hp (298 or 254 kW)

Suspension: Vertical volute spring

Operational range: 120 mi (193 km)

Speed: 24 mph (39 km/h) on road; 15 mph (24 km/h) off road

Variants

M7: 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 storage 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.

M7B1: 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.

M7B2: During the Korean War, the limited elevation of the howitzer became noticeably problematic and it was increased to 65° to increase the effective range of the howitzer. The machine gun mount also had to be raised to give a 360° firing arc.

Defrocked Priest: As one part of the Allied effort to capture Falaise and break out from the Normandy beachhead, a total of 72 M7s had their main guns removed in the field for service as armored personnel carriers and were first used in Operation Totalize. These field modified vehicles were referred to as "Defrocked Priests," "Unfrocked Priests" or as "Holy Rollers." The work was done in one week by 250 personnel from 14 British and Canadian Royal Electrical and Mechanical Engineer units. 36 vehicles each were allocated to the 4th Infantry Brigade of the 2nd Canadian Division and the 154th (Highland) Brigade of the 51st (Highland) Division, which led the attack.

Kangaroo: A Canadian armored personnel carrier 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. A total of 102 were converted between October 1944 and April 1945. The name "Kangaroo" became generic for all conversions of armored fighting vehicles into personnel carriers, including Ram tank conversions.

M7 Howitzer Motor Carriage.

M7 Howitzer Motor Carriage, Philippines.

M7 Howitzer Motor Carriage firing.

M7 Howitzer Motor Carriage M7 loading onto an M19 Tank Transporter for transport from the Mannheim area, Germany, 14 May 1945.

Right side view of M7 Howitzer Motor Carriage, "Finalist."

Rear upper view of M7 Howitzer Motor Carriage, "Finalist."

Left front view of M7 Howitzer Motor Carriage, "Finalist."

M7 Howitzer Motor Carriage during training with a jeep alongside and an artillery observation plane overhead.

M7 Howitzer Motor Carriages in action during training. Note the ammunition trailers being towed by the vehicles.

M7 Howitzer Motor Carriage, Okinawa.

M7 Howitzer Motor Carriage moving toward the front lines near Kasserine.

M7 Howitzer Motor Carriage on railroad flatcar ready for shipment.

105mm Howitzer Motor Carriage, Battery C, 274th Field Artillery Battalion, fires a mission on 1 January near Bastogne.

Loading a 105mm shell into the howitzer of a "Priest" (M7 Howitzer Motor Carriage).

105mm Howitzer Motor Carriage M7 of an American armored unit on the alert near Bastogne. By 27 December more than thirty-five corps artillery battalions were firing approximately 19,000 rounds of ammunition daily in support of the Third Army. By the end of the year that army was supported by over 1,000 guns of 105mm caliber or larger. Christmas night the Third Army's artillery began using the new proximity fuse, which proved particularly effective in interdicting road junctions and harassing enemy positions.

105mm M7 Howitzer Motor Carriage crosses a ponton bridge in Italy.

M7 Howitzer Motor Carriage, Battle of the Bulge.

M7B1 Howitzer Motor Carriage, 12th vehicle, Company C, 423rd or 420th Armored Artillery Battalion, 10th Armored Division, supporting 101st Airborne Division, Bastogne, late 1944.

105mm M7 Howitzer Motor Carriages of the 30th Infantry Division in action near La Gleize, Belgium.

M7 Howitzer Motor Carriage, Company C, 276th Field Artillery Battalion, 6th Armored Division, Third Army, Brulange, France, November 1944.

Overhead view of an M7 105mm Howitzer Motor Carriage. This is an earlier model of the "Priest" but the basic layout was similar for all models.

M7 Howitzer Motor Carriage.

M7 Howitzer Motor Carriage crossing temporary bridge, Remiremont, France, September 1944.

M7 Howitzer Motor Carriage with L-3 observation plane overhead.

M7 Howitzer Motor Carriage.

M7B2 Howitzer Motor Carriage of a Marine unit on the Tientsin-Peiping highway, China, 1946. Carries the name "Millie" on the machine gun pulpit.

M7 Howitzer Motor Carriage in the Ardennes, in front of the Siegfried Line, 1945.

M7B2 Howitzer Motor Carriage.

Deck lashing of M7 Howitzer Motor Carriage, side lashing, turnbuckle attached to wire and to pad eye welded on deck. Fore and aft lashing, turnbuckle attached to towing cleft or hanger, and to pad eye on deck, SS John Calhoun (HR 119), Newport News, Virginia, 1 March 1943.

Fore and aft lashing of M7 Howitzer Motor Carriage, showing turnbuckle fastened to towing clevis of hanger, and by swivel to pad eye welded to deck, SS John Calhoun (HR 119). 1 March 1943.

Deck lashing of M7 Howitzer Motor Carriage, side lashing, 7/8-inch chain attached to turnbuckle which is attached by swivel to welded pad eye on deck, SS John Calhoun (HR 119), Newport News, Virginia, 1 March 1943.

Deck lashing of M7 Howitzer Motor Carriage on SS John Calhoun (HR 119), showing wire attached to body of vehicle about to be fastened by turnbuckle and shackle to pad eye on deck. 1 March 1943.

Deck lashing of M7 Howitzer Motor Carriage, side lashing, turnbuckle fastened by wire to body of vehicle, and by swivel to pad eye welded on deck. Note 12 x 12 cradle of timber. SS John Calhoun (HR 119), 1 March 1943.

M7 Howitzer Motor Carriage.

T32 105mm Howitzer Motor Carriage prototype.

M7 105 mm HMC. Note exposed ammo, protected by fold down armor on later vehicles.

M7 HMC inflatable rubber decoy.

105mm Howitzer Motor Carriage M7 "Priest."

M7 Howitzer Motor Carriage.

M7 HMC with fold down armor and sunken pulpit in use by Canadians, probably in Italy.

American soldiers in M7 Priest enter Cebu City, Philippines.

M7 105mm Howitzer Motor Carriage being tested for desert warfare at Iron Mountains, California. It carries both a 105mm Howitzer and a .50 caliber machine gun. Lieutenant M. Hutchison of Enterprise, Alabama, is at the extreme right. Corporal L. Roberts from Graham, Texas, is at post behind the howitzer. Corporal Downing, whose home is Dekalb, Missouri, is in the turret.

Another view of the same M7 105mm Howitzer Motor Carriage as in the above photo.

M7 105mm Howitzer Motor Carriages roll down the production lines of the American Locomotive Company in Schenectady, New York.

M7 Howitzer Motor Carriage.