WEAPONS OF THE WORLD WAR II GYRENE
M3A1 37MM ANTITANK GUN
During the 1930s, the German and Japanese armies equipped their forces with a variety of tanks and antitank guns. Among these was the German PanzerabwehrKanone 35/36, a lightweight and highly mobile 37mm antitank gun. This weapon was capable of destroying any tank then in service. The US War Department took notice of this weapon and the lack of a similar system in American service.
In January 1937 the US Army Ordnance Department began development of an American weapon similar to the PaK 35/36. Design and testing took place for almost two years. In October 1938 the new 37mm weapon was accepted into service as the M3 antitank gun. Production began the following month and the first guns were delivered early in 1940.
Watervliet Arsenal produced the M3 and by mid–1941 delivered more than 150 guns each month to the Army and Marine Corps. The M3 was manufactured through the summer of 1943 when production was terminated in favor of the M1 57mm antitank gun. Based on combat experience in North Africa, the Army determined it needed the larger gun to defeat German tanks. The Marine Corps continued to use the 37mm throughout the war.
Two models of the weapon were made: the M3 and the M3A1. The latter version had a threaded barrel end to accept a ported muzzle brake. This accessory saw very limited combat service, which showed it was unnecessary. M3A1's could be used without the brake and were issued interchangeably with the M3 version.
In Marine Corps service, the 37mm antitank gun served primarily in the weapons company of the Marine infantry regiment. The first wartime regimental table of organization; the D–series T/O, made no provision for this weapon. Notionally, the regimental antitank/antiaircraft platoon was equipped with 20mm guns, though these were never issued. The 1st MarDiv and its attached 2nd Marine Regiment, organized under the D–series TO for Guadalcanal, were equipped with the M3 antitank gun.
The divisional special weapons battalion under the D– and E–series T/O also had three assigned antitank batteries, each with six 37mm's and two 75mm gun motor carriages. It was intended to attach each of the batteries to the line regiments in the Marine division, but combat deployments in the Solomons showed that the weapons were better assigned directly in the line regiments, and that the guns in the battalion were redundant considering their limited effectiveness against heavy enemy fortifications. The special weapons battalion was deleted from the divisional structure starting with the F-series table of organization.
The D– E– F– and G– series T/O's assigned the 37mm antitank gun in the regimental weapons company. The weapons were issued to the company's three 37mm gun platoons. Each platoon was equipped with four guns. The late war G–series T/O deleted one of the gun platoons, but the 37mm rendered valuable service in every Marine campaign of World War II.
The 37mm antitank was well-suited to requirements of war in the Pacific. It was relatively light and could be manhandled if needed. For example, at Tarawa in November 1943, antitank gunners of the 2nd and 8th Marines towed their weapons and ammo carts by hand across the exposed coral reef and over the seawall. On Bougainville, Marines towed their guns and ammo by hand through jungles to establish defensive positions.
In its primary role defending against Japanese armor, the 37mm was an effective weapon. It could penetrate the armor of any Japanese tank. For instance, on the night of 22 October 1942 on Guadalcanal, 18 enemy tanks with infantry support attacked the Marines of 3/1 at the mouth of the Matanikau River. 37mm antitank guns of Weapons Co, 1st Marines decimated the Japanese tanks from dug-in positions.
In addition to its effectiveness against armor, the 37mm was also a capable weapon against massed Banzai attacks. On Tarawa, Saipan and Guam, 37mm gunners fired canister rounds at close range into massed enemy formations. Working with other assets in the Marine combat team, 37mm helped to form walls of steel that stopped all but the most fanatical and determined enemy troops.
The 37mm's biggest weakness was its lack of power against Japanese field fortifications. It was not able to penetrate most bunkers or pillboxes. Larger weapons, such as the 75mm pack howitzer and tank gun, were better suited to this work. Nevertheless, the 37mm was often called into service against enemy defensive positions.
Five Marines were assigned to each 37mm gun section. A sergeant served as the section leader. He was responsible for designating targets for the gun, and for normal small unit leadership and administration. The gunner was a corporal. He elevated and traversed and fired the gun. The assistant gunner loaded rounds into the breech and could replace the gunner if necessary. Two privates/privates first class were assigned to the section as ammunition bearers. A driver was also assigned for the section's prime mover, usually a jeep.
Marine Gunner Ira Davidson, of Chavies, Kentucky commanded one of the 37mm gun platoons in Weapons Company, 24th Marines, 4th Marine Division. With more than twenty years of service, Davidson knew the 37mm inside and out. During the campaign for Iwo Jima, he put that knowledge to the test.
On 21 February 1945, the 4th Marine Division was locked in battle against strong enemy forces protecting Motoyama Airfield #1. Multiple enemy defensive belts guarded this major complex on Iwo Jima's central plateau. The 24th Marines were assigned to drive to the O-1 line and clear the airfield.
A complex of six pillboxes with mortars in support held up the 1st Battalion, 24th Marines' attack across the airfield, inflicting many casualties. Two M4 medium tanks went forward to knock out the pillboxes. The tanks both hit landmines and were put out of action. Maj Paul Treitel, commander of 1/24, needed support to destroy the pillboxes.
Gunner Davidson reported to the battalion command post. Maj Treitel asked him, "Could you get at those pillboxes with a 37?" The Gunner nodded and moved out. Under mortar and machine gun fire, Davidson crossed the exposed airfield and headed back to his platoon assembly area. He ordered one of his 37mm sections into action.
The Gunner and six of his Marines manhandled their 900 pound gun across 200 yards of fire-swept ground. One of the crew was killed, two were wounded, and another shell-shocked. Once in position, Gunner Davidson took the controls of his gun. Siting in, he engaged each pillbox in turn with 12-15 high explosive rounds each. Under a continuous mortar barrage, Davidson kept shooting until advancing Marines masked his arc of fire.
The infantry Marines moved up and secured the enemy defensive complex. Clearing the pillboxes, they found dead Japanese troops in each. Davidson had fired so accurately, he was able to put rounds through the pillboxes' apertures. His outstanding gunnery skills and leadership saved the lives of many of his fellow Marines. For his heroic actions on Iwo Jima, Marine Gunner Ira Davidson was later awarded the Navy Cross. (1)
Ray Merrell of Marshall, Missouri served from 1942 to 1945 in the Marine Corps and saw combat service in the campaigns on Bougainville, Guam, and Okinawa. He was first assigned to the 2nd Raider Bn. This unit was deactivated on 31 January 1944 on Guadalcanal. Ray and his buddies were assigned as 37mm crew members in the newly reconstituted Weapons Co, 4th Marines. He sent me an e-mail outlining some of his experiences in the Pacific:
"In 1944 after the Bougainville battle, where I had carried a BAR, the Raiders were disbanded. 60% of the 2nd Raider Battalion went into the 4th Marine Weapons Co. I was then an assistant gunner on a 37mm. We trained on Guadalcanal on the 37mm, our guns were set up on the beach and a target was pulled out in the ocean for our target practice.
The night before I got back our gun crew had camped by a Jap beer and saki dump, all the trucks were loaded with beer and saki. The guys had been drinking beer and saki. We moved to the front, set up a big circle of Weapons Company, reinforced by 37mm. Anything out in front of the circle was the enemy. Most of the Marines in the circular defense were sleeping, after drinking all day, except the ones on gun watch. About midnight I was on gun watch when three Japs came walking down the trail right in front of me. I didn't want to make noise loading the gun with a cannister shell, so I picked up a clod of dirt and threw over to Joe Harrison, the truck driver. He was on a machine gun with another Marine.
On June 25th our Weapons Platoon was selected to go out on a mop up of Japanese in the last phase of action. I carried a 40 or 50 pound pack of dynamite to blow the caves shut. We were out like on a big rabbit hunt - hunting Japanese. Three went over a hill and everyone shot, about five or ten minutes later they came down from the hill waving a white rag to surrender, They had been wounded in their arms and legs. That was the end of action on that day. In ten days we were off the island.
NOTE: Ray has written a personal memoir of his World War II service entitled My Three Years in the Marine Corps. It is an outstanding addition to any military library. Ray combines letters, personal photographs, and his memories into a very readable and informative book. Ray's book can be ordered through Scuttlebutt and Smallchow.
Organization of the Marine Infantry Regiment, 15 April 1943
(1) Marine Gunner Davidson's actions on Iwo Jima were documented from his Navy Cross citation, Volume IV, History of USMC Operations in World War II, pg 557, and The Fourth Marine Division in World War II, page 114
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