The newly declassified accounts of the Battle of Iwo Jima reveal a horror far beyond anything previously understood about the flamethrower’s role in modern warfare. What you think you know about this weapon’s effect on the human body is about to be shattered by the truth of what it did to both American and Japanese soldiers in February 1945.
The pre-invasion bombardment of Iwo Jima lasted 70 days, dropping 5,800 tons of bombs on a volcanic island barely five miles long. Japanese defenders, some 21,000 strong, were ordered to make their final stand. They waited inside tunnels carved by hand into soft volcanic rock, breathing sulfur fumes in 100-degree heat while bombs shook the earth above them.
Calling that “waiting it out” demeans their suffering. The real hell began when three U. S.
Marine divisions hit the beaches on February 19, 1945. Lieutenant General Tadamichi Kuribayashi had designed a defensive system that would turn the island into an interlocking 𝓀𝒾𝓁𝓁 zone, making the flamethrower the only weapon that could effectively destroy it.
The Japanese built hundreds of pillboxes, concrete fortifications, and bunkers, all connected by underground tunnels. When Marines tried to clear a pillbox with satchel charges or grenades, the defenders would kick the grenades into special trenches that contained the blast, then resume firing from the same position moments later.
Even when satchel charges killed everyone inside a pillbox, the tunnels allowed reinforcements to reach it from another entrance. Marines would take a position, move past it, and then be shot in the back from the same pillbox they thought they had cleared. There was no clear front line on Iwo Jima.
The only weapon that could seal a pillbox permanently was the flamethrower. The burning stream of thickened fuel, later called napalm, would drip inside through firing slits, splash off interior walls, and run around corners. It didn’t even need to hit a soldier to 𝓀𝒾𝓁𝓁 him.
One year before Iwo Jima, the U. S. Chemical Warfare Service published research called “Mercy Killer,” claiming death by flamethrower was quick and nearly painless.
They said soldiers found dead in pillboxes hit by the flamethrower had barely marked skin, as if they felt no pain. That research was entirely false.
Experiments using pigs and rabbits in mock pillboxes revealed the true mechanisms of death: carbon monoxide poisoning, oxygen deprivation, and breathing in superheated air and vaporized gasoline. These findings were known to military planners, yet the “Mercy Killer” narrative persisted to make the weapon palatable to the public.
On Iwo Jima, Marines developed the “blowtorch and corkscrew” tactic. The flamethrower would fire a “wet burst,” spraying fuel without igniting it, letting it drip deep into a pillbox or cave. Then a second burst would ignite everything at once, causing an internal explosion with devastating effects.
Anyone who saw the aftermath of a flamethrower attack would know the truth was horrific. Soldiers killed this way looked untouched from the outside, but inside their bodies were ravaged by heat and toxic gases. The flamethrower was no mercy killer.
The M2-2 flamethrower used by Marines weighed 70 pounds and gave just seven seconds of fire time. The range was only about 20 yards, meaning the operator had to come terrifyingly close to the enemy position before firing. The pressurized nitrogen tank could burst with enough force to 𝓀𝒾𝓁𝓁 a man if hit by a bullet.
The Japanese quickly learned to target flamethrower operators. Whenever the unmistakable green backpack was spotted, every enemy gun in the area focused on that soldier. If he managed to fire his weapon, the loud, bright stream instantly revealed his position.
If the operator survived his seven-second run and still had not destroyed the pillbox, he was left with only a .45 pistol to fight the enraged Japanese soldiers he had just tried to burn alive. Falling alive into enemy hands as a flamethrower operator was something every Marine avoided at all costs.
The casualty rate among flamethrower operators on Iwo Jima is estimated at 96 percent, with a life expectancy of just four minutes on the battlefield. Trained operators were almost all killed early in the battle, and whoever could carry the weapon was forced to step in as a replacement.
Hershel Woody Williams was one of the few survivors. On February 21, 1945, he was the only flamethrower left in his company. With four riflemen providing covering fire, he knocked out seven pillboxes over four hours, even cutting down a Japanese bayonet charge with his flamethrower.
Two of his covering riflemen were killed, but Williams survived to receive the Medal of Honor. He died in 2022 at age 98.
The vulnerability of backpack flamethrowers led to experiments with mounting them on tanks. By Iwo Jima, eight flame-equipped Sherman tanks had been made ready. These “flame Shermans” carried about 300 gallons of fuel and could fire it over 100 yards, protected from small arms fire by the tank’s armor.
The flame Shermans became what Marines described as a weapon without which they’d never win the battle. They fired 10,000 gallons of fuel every day during the battle. The Japanese had no effective anti-tank weapon to stop them, leading to desperate one-way missions with magnetic mines and satchel charges.
Flamethrowers in both backpack and tank form are credited with roughly 30 percent of Japanese casualties on Iwo Jima. Of the 21,000 Japanese defenders, only about 200 surrendered. The rest died in their tunnels, many sealed in by explosions after the flamethrower had done its work.
The psychological toll on flamethrower operators is a hidden horror. Setting someone on fire from 20 yards away means you see, hear, and smell the consequences of your weapon in vivid detail that the human mind cannot forget. These memories haunted survivors for the rest of their lives.
The battle of Iwo Jima ended on March 26, 1945, with American casualties exceeding those of the Japanese for the first time in the Pacific campaign. The beaches were black ash stained with blood. The tunnels beneath the island still contain the remains of thousands of Japanese soldiers, entombed by the blowtorch and corkscrew.
The “Mercy Killer” research published before the battle was a lie, and those who witnessed the flamethrower’s true effects know it. The weapon was not quick, not painless, and its operators endured a hell that modern audiences can barely imagine. This is the reality of flamethrower warfare on Iwo Jima, revealed now in its full, unvarnished horror.
