On April 19th, 1945, tanks from the 713 tank battalion rolled toward Kakazu Ridge on Okinawa for their first day of combat. The unit had trained for months. They had converted 54 M4 Sherman tanks into flamethrowers at Scoffield Barracks in Hawaii. They had crossed the Pacific anticipating this moment.
Now they would discover what Japanese defenders had learned to do against flame tanks. The smell inside a flame tank was suffocating. diesel fumes, hydraulic fluid, sweat, and the acrid chemical stink of napalm mixing in the fuel system. The temperature exceeded 100° even with the hatches closed. Crews could feel sweat running down their backs, soaking through undershirts and pooling at waistbands.
Hands gripped controls with knuckles white against the metal. Through narrow vision slits, crews watched cave mouths disappear behind curtains of orange flame. The napalm clung to rock, to vegetation, to anything it touched. It burned at temperatures exceeding 2,000°. It consumed oxygen. It created its own weather, sucking air into the inferno and driving superheated gases deep into tunnel networks.
The tanks were part of an armored force attempting to outflank Japanese positions on the ridge. The plan called for them to sweep around the left side of Kakazu, meet infantry on the other side and reduce enemy positions together. But the infantry never arrived. Japanese machine guns and mortars drove back the American foot soldiers, leaving the tanks to operate alone.
That was exactly what the Japanese wanted. The Japanese doctrine was called Nikohhaku Keki, human bullet attack. One soldier, one tank. The defenders understood that fire was consuming their defenses faster than any other American weapon. So they developed the only counter measure available to them, suicide. Throughout the day, Japanese suicide squads attacked the isolated tanks with 22 lb satchel charges.
Soldiers concealed in. Spider holes waited until tanks rolled past, then emerged to attack from behind. Others threw explosive charges onto engine decks or shoved them beneath holes. By afternoon, six tanks had been destroyed by these attacks. Four of them were flame tanks. It was the greatest single day loss of American armor on Okinawa.
Crews who survived their vehicles being disabled faced terrible fates. Japanese soldiers forced turret lids open and threw in grenades. Of the 30 tanks that had maneuvered around Kakazu Ridge that morning, only eight returned to American lines. The crews who survived learned a lesson that would define the rest of the campaign.
Flame tanks needed infantry protection at all times. Without it, they were vulnerable to men willing to die. The Japanese understood this better than anyone. They had been watching flame tanks since Saipan, learning what made them effective and what made them vulnerable. By the time the 713 arrived on Okinawa, Japanese commanders had developed specific tactics for destroying the weapons they feared most.
The problem American forces faced in the Pacific was unlike anything encountered in Europe. German soldiers fought from bunkers and fortifications, but they surrendered when positions became untenable. Japanese soldiers did not surrender. They fought until death. They hid in caves carved into volcanic rock and coral limestone.
They connected those caves with tunnels running hundreds of feet underground. They installed steel blast doors that could withstand direct hits from naval guns. They positioned machine guns and artillery pieces with overlapping fields of fire designed to shred any infantry assault. Conventional weapons were useless against this kind of defense.
On Tarawa in November 1943, American Marines discovered that 3 days of naval bombardment had barely scratched Japanese fortifications. Concrete bunkers remained intact. Steel reinforced pill boxes still bristled with weapons. machine gun nests hidden in palm log imp placements cut down Marines by the hundreds as they waded ashore.
The official casualty count for 76 hours of fighting exceeded 3,000 Americans killed or wounded. The entire Japanese garrison of nearly 5,000 died. The problem at Tarowa was not firepower. American battleships had pounded the tiny atal with 14-in shells. Carrier aircraft had dropped hundreds of tons of bombs.
But the Japanese had prepared for this. They had built positions from coconut logs, coral rock, and reinforced concrete. They had dug into the sand and covered their bunkers with layers of earth that absorbed blast effects. When the Marines came ashore, the Japanese emerged from their shelters and manned their weapons. The Marines learned something critical from Turawa.
Bullets could not penetrate fortified positions. Grenades could not reach deep into cave networks. Bazookas could not collapse reinforced concrete, but fire could. Fire could consume oxygen inside enclosed spaces. Fire could follow the curves of tunnels and reach chambers that no other weapon could touch. Fire could force defenders to abandon positions or die where they hid.
The first American flamethrowers in the Pacific were portable units carried on a soldier’s back. The M2 weighed 68 lb. Fully loaded with 4 1/2 gallons of fuel. It could project flame approximately 40 ft. It was devastatingly effective against bunkers and cave entrances. Marines loved it. Japanese soldiers feared it above all other infantry weapons.
Medical reports from the Pacific documented what happened to defenders hit by flamethrower attack. Those caught directly in the flame stream died within seconds, their lungs seared by superheated air before their bodies even began to burn. Those in enclosed spaces died from oxygen depletion and carbon monoxide poisoning even without direct flame contact.
A single burst into a bunker could kill every occupant without, leaving visible burns on many of the bodies. Naval medical officers examining corpses after flamethrower attacks during the Battle of Saipan found that some victims showed no external burns at all, but had clearly died from respiratory failure. The flames had consumed all available oxygen and filled the enclosed space with toxic combustion gases.
Death came in seconds. The weapon was terrifying in its effectiveness, but the man carrying the flamethrower faced a terrible problem. The life expectancy of a Marine flamethrower operator in combat was approximately 4 minutes. The bright orange flame made him an instant target for every Japanese rifleman and machine gunner within range.
The fuel tanks on his back could ignite if struck by tracer rounds. The limited range of 40 ft meant he had to approach Japanese positions at suicidal distances. Most flamethrower operators did not survive their first engagement. The casualty rate among men carrying the M2 exceeded 90% in some units during the Pacific Island campaigns.
The solution seemed obvious. Mount the flamethrower on a tank. Colonel George F. Unmuted was the chief chemical officer for the central Pacific area in 1944. He worked out of Scoffield barracks in Hawaii where his responsibility included chemical weapons, gas defense, and incendiary warfare. Born in 1887 in Debuke, Iowa, Unmarked had enlisted in the Iowa National Guard at age 16 and spent his career in chemical warfare.
When Japanese aircraft attacked Pearl Harbor on December 7th, 1941, he was among the first officers to reach headquarters directing gas mask distribution to troops who feared follow-up attacks might include chemical weapons. In May 1944, the Navy delivered five Mark1 flamethrowers deemed unsuitable for naval use.
They were too heavy for shipboard application. But Unmak saw an opportunity. If he could mount those flamethrowers on armored vehicles, he could solve the portable flamethrowers vulnerability problem. With assistance from the 170 Naval Construction Battalion, the CBS, Unm assembled a top secret composite unit to develop tankmounted flamethrowers.
Personnel came from the 43rd Chemical Laboratory Company, the Fifth Marine Tank Battalion, and the CBS. The work was unglamorous and dangerous. Engineers had to design mounting systems that could withstand combat conditions. They had to create fuel delivery mechanisms that would not fail under stress. They had to figure out how to protect crews from their own weapon if something went wrong.
Each tank conversion required 1,200 man-h hours of labor. Welders worked around the clock. Electricians rewired 1,00 connections per vehicle. Machinists fabricated 150 custom parts for each installation. The 75 mm main gun was completely removed and replaced with the flamethrower tube. Crews would consist of four men rather than five since no loader was needed.
Machinists made secondass A right and electricians mate secondclass Joseph Kle worked on the early designs. They discovered that the army’s original concepts were overengineered. The CBS simplified the systems making them more reliable and easier to maintain in field conditions. The first prototype was an M3 Stewart light tank with a Ronson flamethrower replacing the main gun.
They called it Satan. The fuel capacity was small. The range was barely better than the portable units, but it worked. A flamethrower protected by tank armor could approach Japanese positions and survive long enough to burn them out. The first Satan was christened hells of fire. Unmarked personally supervised its testing, watching as streams of flame shot from the turret and engulfed target structures.
The heat was intense even from 50 yards away. Men watching the demonstration understood instantly why this weapon would terrify defenders in fortified positions. For the Mariana’s campaign in June 1944, Unmuck’s team converted 24 M3 light tanks into Satans. They were sent to Saipan and Tinan. The results exceeded expectations.
On Saipan, flame tanks proved essential for clearing the island’s countless cave positions. Marines who had watched friends die attacking fortified positions now watched Japanese soldiers run screaming from caves as liquid fire poured inside. The tanks operated in coordination with infantry assault teams. Standard gun tanks provided covering fire and engaged any anti-tank weapons.
The flame tanks approached to within range of the target position, typically 100 to 150 ft. Infantry provided close protection against suicide attackers. When all elements were in position, the flame tank fired. The effect was devastating. Japanese defenders who had survived naval bombardment, artillery barges, and infantry assault could not survive the flames.
Those who tried to remain in their positions died from asphixxiation or burns. Those who fled were cut down by waiting riflemen. Either way, positions that had cost marine lives to assault conventionally fell quickly when flame tanks were available. A first Marine division history recorded the impact plainly. The flame tank was the one weapon that caused the Japanese to leave their caves and rock crevices and run.
The Japanese noticed. Lieutenant General Yoshitsugu Saito commanded the Japanese garrison on Saipan. By early July 1944, American forces had pushed his remaining troops into the northern corner of the island. Seaitto understood that continued conventional defense was impossible. The flame tanks had burned through position after position.
On July 6th, Saito issued his final order. All remaining Japanese forces would conduct Gyokasai, shattered jewel, a mass suicide attack intended to die, inflicting maximum casualties on the enemy. It was the largest bonsai charge of the Pacific War. Nearly 4,000 Japanese soldiers assembled near Makuna village. Many carried rifles.
Some carried only bamboo spears with bayonets lashed to the ends. Wounded men hobbled forward with grenades tied to poles. At 4:45 on the morning of July 7th, they struck the American lines between the first and second battalions of the 105 infantry regiment. The attack lasted 15 hours. Japanese soldiers overran aid stations, artillery positions, and command posts.
They fought with bayonets, swords, and bare hands when ammunition ran out. American machine guns cut them down by the hundreds, but still they came. When it ended, almost every Japanese participant was dead. American casualties reached approximately 900 killed and wounded. Lieutenant General Silito had committed Sepuku the night before, disembowing himself with his sword rather than witness the final destruction of his command.
But the Guyosai at Saipan was not primarily an attack against flame tanks. It was a last desperate attempt to die with honor before annihilation. The Japanese military had not yet developed specific tactics for destroying the armored flamethrowers. That would come later as the flames spread across the Pacific. The true evolution of Japanese anti-lame tank tactics began at Pelu in September 1944.
Colonel Kuno Nakagawa commanded approximately 11,000 Japanese defenders on an island 6 mi long and 2 mi wide. Unlike previous commanders, Nakagawa rejected the traditional strategy of defending beaches and conducting bonsai charges when positions became untenable. Instead, he ordered his men to dig in and fight a war of attrition.
Nakagawa understood something his predecessors had missed. The Americans expected bonsai charges. They prepared for them with interlocking fields of machine gun fire and artillery concentrations. Mass attacks into those kill zones accomplished nothing except the rapid destruction of Japanese forces. But if defenders remained in their fortified positions and forced the Americans to come to them, every yard of advance would cost American blood.
The Umar Brogal Mountain, which Americans would call Bloody Nose Ridge, contained more than 500 natural limestone caves. Japanese engineers connected them with tunnels, installed sliding steel doors over entrances, and modified openings to defend against grenades and flamethrowers. They angled cave mouths so that direct fire could not penetrate.
They created multiple exits so that defenders could escape when one entrance was compromised. The defensive preparations were remarkable in their thoroughess. Mine shafts left over from pre-war phosphate mining operations were converted into ammunition storage and command facilities. Some cave complexes extended hundreds of feet underground with multiple levels connected by staircases cut into the rock.
Ventilation shafts provided fresh air. Electric lighting powered by generators allowed troops to operate in total darkness. Concrete reinforced positions housed artillery pieces that could be wheeled forward to fire through ports, then withdrawn into protective cover. The terrain was nightmarish for attackers. Jagged coral ridges rose at steep angles covered with dense vegetation that concealed defensive positions.
Ravines channeled advancing troops into kill zones. The heat was brutal, often exceeding 100°. Fresh water was scarce and everywhere from every ridge and ravine and cave mouth Japanese machine guns and mortars waited. The first marine division landed on September 15th, 1944. Major General William Rupertus predicted the island would fall within 4 days.
He was wrong by more than 2 months. Initial progress was rapid. Marines captured the airfield on the first day and pushed inland against light resistance. But when they reached the Ummer Bragal, the advance ground to a halt. Colonel Lewis Chesty Puller led his first marines into the ridges, expecting to break through Japanese defenses as they had elsewhere.
Instead, his regiment was systematically destroyed. Puller’s first marines suffered 70% casualties, 1749 men, before being pulled off the line. The regiment was combat ineffective. Flame tanks arrived at Pelleu. Colonel Harold Bucky Harris of the Fifth Marines adopted siege tactics using bulldozers and flamethrower tanks to methodically destroy Japanese positions.
The process was slow, brutal, and effective. Cave by cave, tunnel by tunnel, the Americans burned their way into the Yumemeral. The flame tanks worked forward with infantry escort, approaching cave entrances and pouring fire inside. Some caves required multiple attacks as defenders retreated deeper into tunnel networks only to emerge from alternate exits and resume fighting.
Bulldozers pushed earth and rubble over cave mouths. The process consumed weeks, then months. Colonel Nakagawa sent a final message on November 24th. He reported burning his regimental colors and dividing his remaining 56 men into groups with orders to attack the enemy wherever they found them. That night, 25 Japanese were killed attempting to infiltrate American lines.
The following morning, prisoners confirmed that Nakagawa and Major General Kenjiro Marai had both committed ritual suicide in their command post. But Nakagawa’s men had learned valuable lessons before dying. They observed that flame tanks operated most effectively when infantry accompanied them closely. The escorting soldiers protected the tanks from close assault while the tanks burned fortified positions.
Separate them and the tanks became vulnerable. Japanese doctrine evolved. The Imperial Army developed a three-stage approach to defeating American armor. First, use anti-tank guns to destroy tanks at range if possible. The type 9747 mm anti-tank gun could penetrate Sherman armor at 800 yd, but flame tanks were priority targets.
Knock out the flame tanks first, then deal with the gun tanks. Second, use small arms and mortars to drive away the escorting infantry. Strip the tanks of their eyes. American tank crews had limited visibility from inside their vehicles. Without infantry to warn them of approaching threats, they were vulnerable to close assault.
Japanese doctrine emphasized that the attackers should try to remain concealed until the first volley of small arms had driven off American infantry, then assault the tank. Third, attack the blinded tanks with handcarried explosives, destroy them, or at least immobilize them. Even if the attackers died, the loss of one flame tank was worth many soldiers lives if it meant their comrades could survive another day inside their caves.
Instructors drilled this principle into volunteers. One tank destroyed meant dozens of lives saved. The weapons developed for this purpose ranged from improvised to manufactured. Satchel charges could be thrown onto tank engine decks or shoved beneath tracks. Magnetic mines could be attached directly to hull armor.
Molotov cocktails could ignite fuel and ammunition if they found gaps in armor protection. But the most terrifying weapon was the lunge mine. The Shiatsu Bakarai was a conicle-shaped charge mounted on a 2 m wooden pole. The explosive weighed approximately 3 kg and could penetrate 150 mm of armor at perpendicular impact.
Three metal prongs on the base ensured proper standoff distance for maximum penetration. The total weapon weighed about 14 lb and measured 78 in in length, including the 59in wooden handle. The weapon was officially adopted by the Japanese army in 1944 with first combat use at Lee in the Philippines in December of that year.
A captured Japanese document dated December 13th, 1944 confirmed its deployment. American intelligence analyzed the weapon and characterized it as perhaps the oddest of the Japanese anti-tank charges. To use the lunge mine, a soldier removed the safety pin while approaching the target tank. He held the pole with both hands, explosive tip forward, and charged.
When the prongs struck armor, the handle slid forward into the housing, triggering the detonator. The resulting explosion killed the user instantly while hopefully destroying or disabling the tank. Reports noted that all attempts by Japanese soldiers to use the lunge mine against American tanks had met with failure in early encounters.
American tankers learned to spray likely ambush points with machine gun fire. Infantry accompanying the tanks scouted ahead and protected flanks, but the reports were not entirely accurate. Lunge mine attacks did occasionally succeed, particularly against flame tanks that approached close to cave entrances and ridge positions.
The close range required for flamethrower operations meant flame tanks frequently entered the effective range of suicide attackers who had learned patience and concealment. On Ewima in February 1945, Colonel Unmarked’s team had located only eight M43 Sherman tanks for conversion to flamethrowers. Navy CBS worked frantically to combine the best elements from three different flame units into what they designated the CBH1.
The installation required 150 of welding rod and 1100 electrical connections. Each conversion cost between 20 and $25,000. The new design was superior to the light tank Satans used on Saipan. The Sherman’s heavier armor provided better crew protection. The larger fuel capacity allowed extended operations. The improved flamethrower system operated at 300 lb per square in pressure, giving an effective range of 400 ft with traverse capability of 270°.
Eight tanks for an island defended. By 21,000, Japanese soldiers dug into 11 mi of tunnels and hundreds of interconnected bunkers. General Tadamichi Kuribayashi had prepared Ewoima with meticulous care. He understood that the Americans would eventually take the island regardless of how he defended it.
His goal was not victory. His goal was to inflict maximum casualties and buy time for the defense of the homeland. Every American marine who died on Eoima was one less who would invade Japan itself. The defensive network was extraordinary. Volcanic rock provided natural fortification. Engineers had expanded natural caves and created new ones, connecting them with tunnels that ran beneath the entire island.
Some tunnel complexes reached depths of 75 ft beyond the reach of any bomb or shell. Concrete reinforced positions housed artillery pieces, machine guns, and mortars positioned for interlocking fire coverage. Kuri Bayashi explicitly forbade traditional bonsai charges. The master attacks wasted lives without achieving significant results.
Instead, he ordered his men to make the Americans pay for every yard with blood. Fight from the tunnels. Die in the caves. Kill 10 Americans before you die. His defensive preparations included angling cave entrances to prevent direct flame attack. He ordered construction of multiple tunnel exits so men could escape when one entrance was compromised.
He positioned machine guns specifically to target flamethrower operators. Despite these preparations, the flame tanks burned through his defenses. The eight flame tanks landed with the assault waves. They proved devastatingly effective. Marine reports noted that the flame tank was probably the most valuable single weapon employed at Euima.
The fourth tank battalion reported high success. The fifth tank battalion reported that the new flame tank was an extremely effective piece of equipment. One regimental combat team stated that tanks were probably the most valuable single type of armorament in the operation with flame tanks being more useful than standard gun tanks, especially in the rugged northern areas of the island.
Marines developed assault techniques that became standard doctrine. A flame tank would approach a suspected cave position and fire sustained bursts into the entrance. Infantry would watch for defenders fleeing through alternate exits and shoot them down. Engineers would then move forward with satchel charges and explosives, sealing the cave permanently.
The process was systematic and merciless. Sometimes they could hear screaming from inside. Sometimes they heard nothing at all. Corporal Hershel Woody Williams carried a portable flamethrower on Ewima. He was 5’6 in tall, the youngest of 11 children of a dairy farmer from West Virginia. On February 23rd, Williams singlehandedly assaulted a series of Japanese pill boxes that had stalled his company’s advance.
For 4 hours, he worked forward under constant fire, burning out position after position while only four riflemen provided cover. Two of those riflemen were killed during the assault. Williams returned to his lines five times to refuel his 70 lb flamethrower. He neutralized seven concrete pill boxes, crawling close enough to insert the flamethrower nozzle through the apertures.
Japanese soldiers emerged from their positions with bayonets fixed, determined to stop him. He saw them coming and pulled both triggers on his weapon. They died in the flames. Williams received the Medal of Honor from President Harry Truman on October 5th, 1945 for his actions that day. He passed away on June 29th, 2022 as the last living World War II Medal of Honor recipient. But Williams was unusual.
Most flamethrower operators did not survive sustained combat. The flame tanks provided the same capability with far greater survivability. Marines learned to wait for flame tank support before assaulting, particularly difficult positions. They would hold their advance until a flame tank could be brought forward, then follow the burning path it carved through Japanese defenses.
The Japanese defenders responded with desperate measures. Officers organized nighttime raids specifically targeting the precious flame tanks. Small groups infiltrated American lines under cover of darkness, seeking out the distinctive Sherman silhouettes in assembly areas. Others waited in prepared positions along routes the tanks were likely to travel the following day.
Day after day, the flame tanks consumed 10,000 gallons of napal. They burned bunkers. They incinerated cave complexes. They forced Japanese soldiers out of positions that had survived naval bombardment and aerial attack. When the battle ended after 36 days, nearly 7,000 Americans had died. Japanese deaths numbered approximately 20,000. Captain Frank C.
Caldwell, a company commander with the 26th Marines, summarized the campaign clearly. In my view, it was the flame tank more than any other supporting arm that won this battle. The Japanese survivors of Iuima carried the lessons home. The flame tanks had to be stopped. Okinawa would be the proving ground. Lieutenant General Mitsuru Ushiima commanded the Japanese 32nd Army on Okinawa.
He had studied the failures at Saipan, Pelu, and Iuima. He understood that beach defense was futile against American naval firepower. He recognized that the only viable strategy was defense in depth, forcing the Americans to pay for every ridge and cave with blood. Ushiima was a professional soldier who had commanded forces in China and Burma.
He had seen what American firepower could accomplish. Unlike some Japanese commanders who believed spiritual power could overcome material disadvantage, Ushima was a realist. He prepared his defenses accordingly. The Shri line was his masterpiece. Named for Shri Castle at its center, the defensive network stretched across the southern portion of Okinawa.
It incorporated natural terrain features, reinforced concrete pill boxes, interlocking fields of artillery fire, and hundreds of cave complexes connected by tunnels. General Simon Bolivar Buckner, commanding the American 10th Army, later described it as arguably the most formidable defensive position ever encountered by Americans on any of the Pacific islands.
The statistics were staggering. The Japanese had constructed over 60 mi of tunnels beneath the ridges. Some tunnel complexes extended to depths of 100 ft or more, completely immune to bombardment. Artillery positions were dug into reverse slopes where naval gunfire could not reach them. Machine gun positions covered every approach with overlapping fields of fire.
For this campaign, the army decided that an entire tank battalion would convert to flame. The 713 tank battalion was created from the third battalion 42nd armored regiment of the 11th armored division. The regiment had been organized on August 15th, 1942 at Camp Pulk, Louisiana while the rest of the division deployed to Europe.
The 713 headed for the Pacific. Lieutenant Colonel Thomas L. M. Kra of Arlington, Virginia commanded the battalion. On November 10th, 1944, he received orders to convert all 54 of his M4 Sherman tanks to flamethrowers. This would be the first and only tank battalion in the world equipped entirely with flame tanks.
At Scoffield Barracks, CBS supervised the conversion using Canadian Ronson systems. Three officers and 60 enlisted men from the battalion worked alongside the CBS, learning maintenance procedures and operational techniques. The Ronson flamethrowers had shorter range than the CBH1 used at Ewaima, approximately 80 to 100 yards compared to 120 to 150 yards for the Hawaiian design systems, but they were available in quantity.
The first converted tank arrived on December 25th, Christmas Day. All 54 were completed by January 25th, 1945. The battalion trained intensively during the conversion process. Colonel Unmuk’s chemical warfare service personnel conducted comprehensive 40-hour courses on flame tank operation, maintenance, and tactical employment.
Crews learned to coordinate with infantry escort. They practiced approaching fortified positions. They trained on fuel management, target selection, and withdrawal procedures. The hose extension was a particular innovation, allowing operators to reach pockets of defenders that could not be flamed directly.
Navy fire hose in 50 ft lengths gave tanks up to 400 ft of reach. The battalion departed Pearl Harbor on March 4th, 1945 aboard 10 landing ships. Crucial items of ammunition, fuel, rations, and supplies were divided among the ships to ensure that the loss of any single vessel would not [ __ ] the unit. One tank was lost when it drove into a hole on the reef during unloading and was deemed unreoverable.
The battalion would begin the campaign with 53 flamethrower tanks. The 713 was in action continuously from April 7th to June 30th, 1945. 85 consecutive days of combat. Its mission was to support both Army and Marine Corps infantry in assaulting the Shuri line. Each company of tanks would be parcled out to frontline units as needed.
Ushiima had organized independent anti-tank companies specifically for suicide missions against American armor. These units were formed from volunteers who understood they were not expected to survive. They were taught to embrace death as the highest form of service to the emperor.
Their training emphasized a specific sequence. drive off the infantry with small arms and mortars, leave the tanks blind, then attack with explosives. The volunteers came from units that had seen what flame tanks could do. They had watched flames pour into caves where their comrades were hiding. These men understood that death by fire was terrible beyond description, and they were willing to die to prevent it from happening to others.
Japanese soldiers wrote final letters to their families before suicide missions. They performed purification rituals. They made peace with death before they went to die. Some of those letters survive, preserved in museum collections. They speak of duty and honor, of love for family and homeland, of acceptance of fate.
They do not speak of fear, though the fear must have been overwhelming. The tactics had evolved significantly since Saipan. Japanese soldiers no longer charged blindly at tanks in the open. Instead, they concealed themselves in fighting positions along likely tank approaches. They waited until American infantry moved forward past their positions.
Then they emerged from spider holes and concealed entrances to attack the tanks from behind or from the flanks. Concealment was essential. A soldier would dig a shallow hole just deep enough to lie flat with minimal profile. He would cover himself with vegetation, rocks, or dirt, until he was invisible from more than a few feet away.
He would remain motionless for hours, sometimes days, waiting for a tank to approach within striking distance. He would control his breathing, ignore thirst and hunger, suppress every natural instinct to move or adjust position. Some soldiers concealed themselves in spider holes directly in the path of advancing flame tanks.
When a tank rolled overhead, the soldier would rise, detonate explosives, and die while attempting to destroy the vehicle. Others waited in bottle-shaped holes that allowed them to stand upright, but remain invisible until the moment of attack. When the moment came, the attacker would have only seconds to act, rise from concealment, pull the fuse or igniter, close the distance, deliver the charge. The explosion would kill him.
If he was lucky, it would destroy the tank as well. The satchel charge was the most common weapon. A cloth bag filled with explosives and fitted with a short fuse. It could be thrown onto the engine deck where the armor was thinnest. Alternatively, a soldier could dash beneath a tank and place the charge against the belly armor before detonating it.
Either method usually killed the attacker, but both could disable or destroy a tank. Japanese engineers studied captured American tanks to identify their weakest points. They learned that the Sherman’s engine deck was vulnerable to concentrated explosive attack. They discovered that the tracks and suspension could be destroyed by charges placed against the road wheels.
They found that ammunition stored in certain locations could be detonated by explosives placed against the hull. The type 99 magnetic demolition charge was particularly feared by American tank crews. It consisted of eight separate sticks of TNT assembled in a circle with four powerful magnets attached by canvas ribbon.
The total weight was approximately 43 oz with 26 oz of explosive. A soldier would approach a tank from a blind spot, slap the charge against the hull, and retreat if possible or detonate in place if not. The charge could penetrate threequarters of an inch of armor when used singly or one and a/4 in when two charges were stacked together.
This was sufficient to breach the Sherman’s thinner armor on the engine deck, belly plate, or rear. A 5 to 10 second time delay fuse gave the attacker a chance to escape, but many chose to remain and ensure the charge detonated against a vital point. Other soldiers attacked with Molotov cocktails, hoping to ignite fuel or ammunition through vision slits or ventilation openings.
Some carried nothing but hand grenades, attempting to overwhelm crews by sheer numbers. Officers led groups in coordinated attacks, sacrificing themselves to ensure at least one man reached the target. The flame tanks presented a particularly difficult problem for Japanese defenders, but also the greatest opportunity.
Their crews understood the danger they faced and developed counter measures. Infantry escort remained close at all times before approaching Japanese positions. Tankers sprayed likely ambush points with machine gun fire or flame. They coordinated closely with artillery and mortar teams to suppress enemy movement, but the nature of flamethrower operations required the tanks to approach close to targets.
The effective range of the Ronson system was approximately 80 to 100 yardds, but for maximum effectiveness against cave entrances, much closer ranges were necessary. This brought the flame tanks within the kill zone of suicide attackers. The attack at Kakazu Ridge on April 19th demonstrated the vulnerability perfectly.
When infantry support failed to materialize, Japanese suicide squads destroyed tank after tank. Crews who survived their vehicles being disabled often faced worse fates. Japanese soldiers forced turret lids open and threw in grenades, killing men trapped inside. The battalion adapted. Tactics evolved through bloody experience.
Flame tanks would remain in forward assembly areas until called forward by platoon leaders. They would join with standard tanks and infantry only when all elements could move together. The infantry remained close at all times, watching for suicide attackers while the flame tanks burned Japanese positions. General Simon Bolivar Buckner, commanding the American 10th Army, described the tactics as blowtorrch and corkcrew.
The blowtorrch was the flame tank spraying napal mixture into caves where it stuck to everything it touched. The corkcrew was demolition charges planted to collapse the cave and seal it permanently. Together, they reduced Japanese positions one by one. The commanding general of the seventh infantry division reported to Colonel Unmak of one incident where a captain and sergeant under covering fire reached the top of an escarment with a hose extension and killed several hundred Japanese soldiers with the deadly flame.
The hose extension proved essential for reaching pockets of defenders that could not be flamed directly from tank positions. Flamethrower tanks were used for flaming forward and reverse slopes of hills and escarments, clearing fox holes and bottle-shaped spider holes dug in the earth, cliff caves, and ruins of structures.
The 43 chemical laboratory company had developed a stabilized flamethrower fuel, napalm, and oversaw construction of an activating plant that produced over 250,000 gallons for the campaign. This pattern repeated across Okinawa throughout the spring of 1945. The 713 tank battalion killed 4788 Japanese soldiers and captured 49 during the campaign.
They burned out hundreds of caves and fortified positions. Battalion losses were comparatively light given the intensity of combat. Eight men were killed or missing. 111 were wounded. Enemy anti-tank fire and mines claimed 16 of the battalion’s tanks. Another 25 were listed as operational losses. Of the 41 total knocked out, 26 were returned to duty.
On the last day of operations, June 30th, the battalion had 37 operational tanks. The ingenuity and hard work of mechanics had kept the unit at over 70% strength after almost 3 months of continuous combat. This was remarkable considering no replacement flame tanks existed anywhere in the theater. The battalion used over 200,000 gallons of napalm.
They received a presidential unit citation for their actions. Company B received two additional presidential unit citations from the Navy for operations with marine divisions. Buckner did not survive to see the end of the campaign. on June 18th, 1940. Five, he was observing frontline operations near Ibaru Ridge when Japanese artillery found his position.
A 47 mm shell struck a nearby coral outcropping. Fragments pierced his chest. He died 10 minutes later. The highest ranking American officer killed by enemy fire during the war. The Japanese commander, General Ushima, committed Sepuku on June 22nd. His chief of staff, General Isamu Cho, died beside him.
The battle for Okinawa was officially declared over the following day. The casualty figures told the story. American ground forces suffered approximately 49,000 killed, wounded or missing. 12,520 were killed or missing in action. The Navy lost another 5,000 dead and another 4,900 wounded to kamicazi attacks and conventional air strikes.
Japanese military deaths exceeded 107,000. Another estimated 23,000 were sealed in caves and never recovered. Approximately 140,000 Okinawan civilians died, caught between the two armies. That was nearly 20% of the island’s population. The battle had lasted 82 days. It was the largest amphibious assault in the Pacific War, involving more than 180,000 American combat troops.
Every day brought new nightmares. Kamicazi attacks sank or damaged hundreds of ships. The destroyer USS Lafi earned a nickname the ship that would not die after surviving attacks from 25 enemy aircraft. Infantry fought for yards of ground that had no names, only numbers or grim nicknames. Sugarloaf Hill, Hacksaw Ridge, Shuri Castle.
Each one a killing ground where men died by the dozens for positions measured in feet. The flame tanks had proven their worth beyond any question. They could do what no other weapon could. Reach into the deepest caves and force defenders out or kill them where they hid. According to the men on Okinawa, the armored flamethrower’s value lay in its ability to drive the Japanese out of prepared positions into the open to be killed by supporting troops.
American commanders stated unequivocally that the tanks saved lives. The psychological impact cut both ways. American troops came to rely on flame tanks, sometimes refusing to advance against fortified positions until armored fire support was available. Japanese defenders learned to fear the sound of Sherman engines, the smell of napalm, the roar of flame.
Some abandoned positions at the mere approach of a flame tank. Others waited in their caves with explosives, determined to take the hated machines with them when they died. But the Japanese response had also proven effective in its own terrible way. Suicide attacks against flame tanks slowed the American advance and destroyed irreplaceable equipment.
Each tank lost represented not just the vehicle but the trained crew, the specialized fuel and parts, the coordination with infantry that had been developed through bloody experience. Both sides were trapped in a logic of escalation that led only to more death. The Americans developed weapons to burn defenders out of fortified positions.
The Japanese responded with suicide attacks against those weapons. The Americans improved their tactics and built more flame tanks. The Japanese organized specialized suicide units and distributed more explosives. The cycle ended only when the war itself ended. After Okinawa, planning began for the invasion of Japan itself.
Operation Downfall, the projected assault on the home islands, would require thousands of tanks and hundreds of thousands of troops. Military planners anticipated casualties in the hundreds of thousands, possibly millions. Some estimates suggested American dead alone could exceed half a million. The flame tanks would be essential.
Military assessments from Okinawa made clear that the weapons had broken defenses that could not be broken by any other means. They had forced an enemy that refused to surrender to flee or die. They had saved countless American lives by eliminating positions that would have required infantry assault at terrible cost. The Japanese were preparing their own response.
Suicide tactics that had developed in the island campaigns would be expanded to a national scale. Every civilian would be mobilized for defense. Men, women, and children would be armed with bamboo spears, explosive charges, any weapon available. The doctrine was clear. 100 million shattered jewels. The entire nation would die before accepting surrender.
Under Secretary of War Robert Patterson placed an expedite on Colonel Unmak’s production of flame tanks. In June 1945, the army had canled all further production orders for standard M4 Shermans. This caused Patterson to intervene directly. The flame tank project received AAA procurement priority, the same classification given to the B29 bomber and the atomic bomb.
This was the highest emergency rating in the war production board system. Another 72 flame tanks were ordered by the Marine Corps. By victory over Japan Day, Onmak’s crews had 70 ready for shipment. In total, the CBS at Scoffield barracks had produced 354 flame tanks during the war.
The CBS who built those tanks worked around the clock. They understood what the weapons would be used for and what they would face. They understood that every tank completed might save dozens of American lives. They fabricated parts, welded armor, installed flamethrowers, and tested systems with the same dedication they had shown throughout the war.
They were never needed. The atomic bombs dropped on Hiroshima, and Nagasaki ended the war before the invasion could begin. Emperor Hirohito announced Japan’s surrender on August 15th, 1945. The planned apocalypse of Operation Downfall never occurred. Colonel George F. unmarked remained in Hawaii after the war serving as chief chemical officer until his death in January 1954 at Tripler Army Hospital.
He was buried at the National Memorial Cemetery of the Pacific with full military honors. In 1995, he was postumously inducted into the US Army Chemical Corps Hall of Fame. The weapons his team created set the standard for American mechanized flamethrower operations through the Korean War. When communist forces invaded South Korea in June 1950, the Marine Corps assembled a platoon of nine flame tanks from survivors of Unmarked wartime production.
These were CWSPH5 tanks from the 26 the Marines had received during World War II. Gathered from Pendleton and Hawaii called the Flame Dragons, they formed a platoon attached to headquarters, First Tank Battalion. They landed at Inshan in September 1950 in the second wave on Womido Island and participated in the first battle of Seoul.
They were the only United States mechanized flame unit to serve in the Korean War. North Korean soldiers attacking American tanks with satchel charges strapped to their bodies. Discovered that the tactics of the Pacific War still being practiced. The flame dragons burned enemy positions just as their predecessors had done on Okinawa 5 years earlier.
It was not until 1955 that a superior design, the M67, based on the M48 patent tank, replaced the Shermans the CBS had built in Hawaii. The United States military continued to field flamethrower tanks through the Vietnam War, where M67 Zippos burned enemy positions in the jungles and villages of Southeast Asia. In 1978, the Department of Defense unilaterally discontinued flamethrower use.
Public opinion had turned decisively against weapons that burned people alive. No treaty required the decision. No international law mandated it. The United States simply chose to stop using a weapon it had employed to devastating effect for three decades. Vietnam marked the last American combat use of flamethrowers.
The M9-7 was the final infantry flamethrower model. The caves of Okinawa are quiet now. The ridges where thousands died have grown over with vegetation. Tourists visit Shuri Castle, rebuilt in 1992 after its destruction in the battle. Peace memorials honor the dead of all nations. The cornerstone of peace monument lists 234,183 names.
Everyone who died, Japanese, American, Okinawan, regardless of nationality or allegiance. More than 140,000 were Okinawan civilians. Old men sometimes return. American veterans who fought in the caves. Japanese survivors who hid in the tunnels. They walk the same ground where they once tried to kill each other. They stand at memorials and remember friends who did not survive.
Most do not speak of what they experienced. The words do not exist for what they saw and did. Some caves remain sealed to this day. The bodies inside were never recovered. Engineers during the battle estimated that thousands of Japanese soldiers were intombed in collapsed tunnels buried under tons of rock and earth.
Explorers occasionally find artifacts, rifles, helmets, human bones. The island keeps yielding its dead decade after decade. At the National Museum of the Pacific War in Fredericksburg, Texas, exhibits document the flame tank operations. A Mark 2 portable flamethrower sits in a display case. It looks almost harmless. a metal backpack with tanks and tubes.
Visitors read the placard and learn that it could throw fire 40 ft. Most do not understand what that means until they see photographs of it being used at Fort Leonardwood, Missouri. Preserved examples of the POAWSH1 and POAWSH5 stand as monuments to what Unmar’s team accomplished. Young soldiers walk past them on their way to classes.
Few stopped to consider what these weapons represented. The Japanese self defense force does not use flamethrowers.
