To the Marines on the ground during the battle for Iwo Jima in February 1945, the Sherman M4A3 medium tank equipped with the Navy Mark I flamethrower was the best thing going. The Marines had come a long way in the tactical use of fire in the 15 months since Tarawa, when only a handful of backpack flamethrowers were available to combat the island's hundreds of fortifications.
The Iwo Jima landing force still relied on portable flamethrowers, but many Marines saw the value of going one step further and marrying the technology with armored vehicles.
In the Mariana Islands in 1944, the Marines modified M3A1 light tanks with the Canadian Ronson flame system to good effect; the problems came instead from the vulnerability of the small vehicles. At Peleliu, the 1st Marine Division mounted the improvised Mark I system on a thin-skinned LVT-4; again, vehicle vulnerability limited the system's effectiveness. The solution seemed to lie in mounting the flamethrower on a medium tank.
The first modification to Sherman tanks involved the installation of the small E4-5 mechanized flamethrower in place of the bow machine gun. This was only a marginal improvement; the system's short range, modest fuel supply and awkward aiming process hardly offset the loss of the machine gun. Even so, each of the three battalions employed E-4-5-equipped Shermans during the battle for Iwo Jima. The best solution came from an unlikely joint task force of Navy Seabees, Army chemical-warfare service technicians and Marine tankers in Hawaii.
According to Lt. Col. William R. Collins, commander of the 5th Tank Battalion, this inspired group modified the Mark I flame thrower to operate from within the Sherman's turret, replacing the 75mm main gun with a look-alike launch tube. The modified system could then be trained and pointed like a conventional turret gun. Unfortunately, the ad hoc modification team had only sufficient time and components to modify eight M4A3 tanks with the Mark I flame system; four each went to the 4th and 5th Tank Battalions. The 3rd Tank Battalion, then in Guam, received neither the M4A3 Shermans nor the field modifications in time for Iwo Jima, although a number of their A2 tanks had the bow-mounted E4-5 system.
The eight modified Sherman flame tanks proved ideal against Iwo Jima's rugged caves and concrete fortifications. The Japanese feared this weapon greatly; time and time again suicide squads of "human bullets" would assail the flamethrowing tanks directly, only to be shot down by Marine riflemen or scorched by the main weapon.
Enemy fire and the rough terrain took their toll on the eight flame tanks, but maintenance crews worked around the clock to keep them running. In the words of Capt. Frank C. Caldwell, a company commander with the 26th Marines: "In my view, it was the flame tank more than any other supporting arm that won this battle." Demands for the flame tanks never diminished.
Late in the battle for Iwo Jima, as the 5th Marine Division cornered the last Japanese defenders,the 5th Tank Battalion expended 10,000 gallons of napalm-thickened fuel per day. The division's final action report stated that the flame tank was "the one weapon that caused the [Japanese] to leave their caves and rock crevices and run."
Fuel hose stretches up hill
Tanks advance up hill
Flame hits hill
Burned out Japanese survivor
Enemy position burned out
