History of Tank Mounted Flamethrowers
M2 Medium Tank, with E2 flamethrower installed in place of the 37mm main gun, during 1941 test.
Interest in a flamethrower mounted on an armored platform began in World War I. The flamethrower is uniquely able to assault deep fortifications -- caves, bunkers, tunnels -- and drive out determined defenders. By 1940, this capability was seen as necessary for the coming war in both the Pacific Theater against the Japanese and the European Theater against the Germans. Chemical Warfare Technical Committee laid down tentative military characteristics and in the summer of 1940 engineers constructed a weapon. Tests with this flame thrower uncovered flaws which were corrected in a second model, installed in an M2 medium tank.
However, prior to 1944 application of flame throwers in combat by the US Armed Forces was generally confined to the use of short-range, low-capacity portable units employed directly by ground troops or by improvised installation in available armored vehicles. Before flamethrowers were mounted on the M4 Sherman medium tank, experimental models were mounted on M3 and M5 light tanks and LVT amphibious tractors. These attempts were not fully successful due primarily to the light armor of the vehicles. Defending forces could too easily identify and defeat the flamethrower. Something heavier was needed to fight at close quarters with a dug-in, determined enemy armed with satchel charges and antitank guns.
Tank mounted flamethrowers were tested in limited numbers during operations on Saipan, Peleliu, the Philippines, and Iwo Jima. Success there continued the momentum toward a standardized approach. But it was not until the Okinawa Campaign in the Ryukyus (April 1945) that sizable numbers of a robust flamethrower were fielded on the survivable platform of the M4 Sherman tank.
Developments in Allied nations contributed to the US flamethrowing tank effort. By 1944, the British had designed and used their flamethrowing Churchill tank (called Crocodile) in the European Theater. Crocodile carried its fuel in an armored trailer and could project a jet of flame over 150 yards. American observers recorded the successes of these main armament flamethrower tanks against the Germans and sent reports to the Chief of the Chemical Warfare Service.
In addition to man-portable flamethrowers for infantry, two general types of tank-mounted flamethrowers were developed in parallel during the WW II timeframe:
- Auxiliary Mechanized Flame Throwers
- Main Armament Mechanized flame Throwers
Auxiliary units fired through the bow machine gun port or periscope. Main armament flamethrowers were mounted in the turret, in place of the main gun. Both approaches went through rapid design evolution, trying various approaches. Portable flamethrowers were adapted to the purpose, but had limited range and fuel capacity. Larger units were developed specifically for installation in tanks and these were far more successful. Units were produced for the M3, M4 and M5 tanks with the M4 Sherman platform becoming the most successful.
Development and Use of the M4 Sherman Flamethrower Tank in World War II
M4 Sherman Tank equipped with flamethrower fitted to the bow machine gun ball-mount, circa 1944.
Initial efforts were field improvisations of Auxiliary Mechanized Flame Throwers, based on components of available portable flamethrowers. In October 1943, the Chemical Warfare Service modified the portable flame thrower to fit the bow machine gun ball-mount, creating the first standard tank flamethrower, adapted to M4 Sherman as well as M3 and M5 light tanks. In the field, it took several hours to install fuel reservoirs, but thereafter the operator could remove the machine gun and insert the flame gun in a minute or two. The flame thrower could fire one gallon of fuel per second to an effective range of 25 to 30 yards with oily fuel, 50 to 60 yards with thickened fuel. The CWS procured 1,784 model M3-4-3 bow flame throwers with fuel capacity of 50 gallons for M4 Sherman tanks. These bow-type flame throwers saw action in the European Theater, in the Marianas operation (Guam), on Peleliu, Luzon, and other islands.
Some tank commanders rejected the bow flame thrower because use of the important bow machine gun was lost. An alternative was to mount the flame gun in the turret alongside the periscope. In Hawaii, the CWS, Seabees, and their contractors produced several periscope models, one of which (M3-4-E6R3) went into standardized production in 1945, but was too late for use before the end of the war. A total of 176 units manufactured locally in Hawaii were employed in the Ryukyus campaign (Okinawa).
Development of Main Armament Mechanized flame Throwers began slowly due to the low priority given the project in competition for wartime resources. Few tanks were made available to modify. Tests in mid-1942 with an M3 medium tank helped identify improvements and by the beginning of 1943 there were two fairly satisfactory main armament flame throwers. The first one was developed by CWS as the E7 and a second unit sponsored by the National Defense Research Committee (NDRC) called Q (for Quickie), produced under CWS contract by Standard Oil Development Company. In March 1943 CWS arranged a demonstration for Army Ground Forces to decide which of the two models it preferred. Q was selected. The Army decided to place the flame thrower in light tanks, the only tanks available, and a complete system was devised for the M5A1 Stuart. The flame gun, fuel reservoir, and compressed gas cylinders were mounted in a turret basket that was interchangeable with the regular turret basket of an M5A1 tank. The reservoir held 105 gallons of fuel that could be discharged at a rate of approximately two gallons per second. The range with ordinary fuel was 30 to 40 yards, with thick fuel 105 to 130 yards. However, continuing difficulty in obtaining tanks to modify delayed the installation of flame throwers. It was January 1944 before the Armored Board received a weapon for test. By that time, the M5A1 tank was considered obsolete, forcing the CWS and NDRC to start over and design a flame thrower for the M4 Sherman medium tank.
The work went forward slowly because the Army wanted all tanks shipped to the war zones, the CWS lacked engineers for the project, and considerable time was needed to perfect the complex mechanism. Finally representatives of CWS, AGF, ASF, and NDRC agreed that the fastest way to get a main armament flame thrower into action was to have Standard Oil modify the earlier Q, creating a new system known as the Mechanized Flame Thrower E12-7R1, later standardized as the M5-4. This modification was done rapidly, but the M5-4 could not be installed until the spring of 1945 because tanks were still scarce. The war ended before the flame throwing M4 Sherman tank of this design could be shipped overseas. Four NDRC Q model (E7-7) flame throwers mounted in M5A1 light tanks left over from testing were shipped to Manila, Philippines, arriving 3 April 1945, the only flame tanks used in the war that were produced in the US mainland.
The delays in getting flamethrower tanks from the standard sources in the United States, led to a flurry of expedient developments in the field. The most significant effort was in Hawaii, a collaboration between the Army CWS and the Navy, under COL George H. Unmacht, CWS, after Jan 1944. They adapted the Ronson flame thrower, developed in Great Britain in 1941 and improved by the Canadians. NDRC adapted the Q flame unit for the Marine Corps, renamed the Navy Mark I, first five units of which reached Hawaii in April 1944. The first tank, an M3A1 Stuart, was fitted with the Ronson flamethrower and named Satan. Twenty-four Satan tanks were shipped to the Marines and used on Saipan in June 1944, then on Tinian, with good success.
In September 1944, the Tenth Army was planning an attack on Formosa, later canceled. They requested that large capacity flame throwers be installed in fifty-four M4 Sherman medium tanks. In the first model the 43d Chemical Laboratory Company installed a Ronson gun like the one used on Satan. The Tenth Army pointed out that the silhouette was different from the 75mm gun of the regular M4 tank, and this would permit the enemy to selectively target flame tanks. 75mm gun tubes were in short supply; only a few salvaged tubes were available. Seabees machined these for the purpose until COL Unmacht obtained authority for additional serviceable tubes.
The new M4 Sherman flame thrower tank, designated POA-CWS "75" H-1 or POA-CWS-H1 (POA for Pacific Ocean Areas, CWS for Chemical Warfare Service, H for Hawaii), used the US Navy Mark 1 flamethrower system, based on the Q design E14-7R2. It was demonstrated to the Tenth Army about 1 November 1944. The weapon used compressed carbon dioxide gas to propel the fuel, had a fuel capacity of 290 gallons, a range of 40 yards with oily fuel and 60 to 80 yards with thickened fuel. Eight M4A3 Shermans modified with the POA-CWS-H1 were sent to the Fleet Marine Force, Pacific, for the Iwo Jima operation and 54 were supplied to the 713th Provisional Flame Thrower Tank Battalion for the Ryukyus operation (Okinawa).
M4A1 Sherman medium tank from the 713th Tank Battalion, equipped with POA-CWS-H1 flamethrower (Marine Corps design M4A3R5), firing at the entrance of a cave on southern Okinawa, 25 June 1945.
On Iwo Jima (Feb 1945), Marines found the flame tanks particularly helpful in the later stages of the operation when they had to take a network of caves. By the time the Marines had reached the northern end of the island, flame tanks had proven so useful that demand for them exceeded the supply. On Okinawa the operations took place on the hilly southern portion of the island where Japanese troops had defenses in cliffs, hills, and escarpments. The 713th Tank Battalion carried out more than six hundred attacks, and fired almost 200,000 gallons of napalm thickened fuel.
In another field expedient, troops on Okinawa employed an ingenious hose extension against caves that were out of range of tanks. The Navy donated fifty-foot lengths of fire hose which the men coupled together to form a hose four hundred feet long. They fastened one end of the hose to the fuel reservoir of the tank, and attached an M2-2 portable flame gun to the other end. In action, the M4 Sherman tank parked as close as possible to the target, the operators dragged the hose to a position within range, the tank pumped fuel through the hose, and the nozzleman ignited the fuel and directed the flame at the target. The extension was used with good results on a number of occasions.
During World War II several other significant development projects attempted to improve the M4 Sherman as a flamethrower tank, including the Sherman Crocodile with an armored fuel trailer, the T33 variant converted from M4A3E2 tanks, and an effort at the University of Iowa to produce a Sherman with dual main gun and flamethrower.
M4 Sherman Flamethrower Tank After World War II
Two M4A3E8 Sherman tanks, with POA-CWS-H5 double barrel flamethrower equipment, from the Flame Platoon, First Tank Bn, First Marine Division, Korea, circa 1950.
After use in the field, commanders objected to main armament flame throwers chiefly because they replaced the tank's main gun. To meet this criticism, COL Unmacht's staff drew up plans for mounting flame throwers alongside the gun instead of replacing it. Work began in late 1944 when Fleet Marine Force, Pacific, anticipating an invasion of Japan, asked for at least seventy-two main armament flame throwers. Most of the tanks provided by the Marines carried 75mm guns, the remainder carried 105mm howitzers. By judicious planning, designers arranged the interior of the vehicles to allow the storage of forty rounds of 75mm or twenty rounds of 105mm shells without decreasing the quantity of flame-thrower fuel. Handicapped by a scarcity of parts and a dearth of machinists and other craftsmen, the work proceeded slowly. During the battle on Okinawa the Tenth Army asked for eighteen of these double-barrel M4A1 Sherman tanks, designated POA-CWS-H5. They were on their way to that island by the time the battle ended, and were rerouted, instead, to the Marianas to equip the Marine division rehabilitating there. Seventy tanks were ready for the invasion of Japan when the operation was called off and the war came to an end.
The rapid demobilization after World War II ended terminated interest in the M4 Sherman flame tanks. The Army was left with none, but the Marine Corps kept a small number of the double-barreled M4A3E8 Shermans equipped with 105mm main gun with the POA-CWS-H5 flame system alongside. When the Korean War began in June 1950, the Marine Corps hurriedly formed a platoon of nine flame tanks within its First Tank Battalion. These tanks were pulled from storage in Hawaii and California, then accompanied the Marines in the Inchon Landing, 15 September 1950. In Korea, the M4 Sherman flame tanks made a heroic contribution, described in the book Hearts of Iron: The Epic Struggle of Teh 1st Marine Flame Tank Platoon: Korean War 1950-1953.
Some sources report that there were Ordnance standard model numbers assigned to M4 Sherman tanks converted to flame tanks: M42B1 (converted M4A1) and M42B5 (converted M4A3).
Find additional photos and hi-res versions of the M4 Sherman flamethrower tanks at the Olive-Drab Military Mashup.
Note: Material on this page adapted from U.S. Army in WW II: Chemical Warfare Service, Chapter VII Flamethrowers, Flamethrower Tanks on Okinawa, ARMOR: January-February 1994, Steven Zaloga's Armored Thunderbolt
, Standard Oil Co. E12-7R1 Report OSRD 6350, 1945 and other sources.