Marine Tanks at Okinawa and the Armored Angels of Kunishi Ridge

The final trial for Marine tankers in World War II began with a titanic amphibious landing on the Japanese island of Okinawa on L-Day—April 1, 1945. Amongst the 180,000-strong initial landing force of the 10^th Army were Marine 1^st and 6^th Tank Battalion—equipped with diesel-engine M4A2 and gas-powered M4A3 tanks respectively—and eight Army tank battalions.

These units would soon assume a major role in the bloodiest conflict of the Pacific Theater—but for some of those tankers, their introduction to the battle was anything but fast and furious.

Though the Marine Corps was accustomed to landing individual tanks using LCM (Landing Craft Mechanized), it profited from massive landing operation to combat test an alternative innovation: the pontoon-based T6 flotation device which allowed a Sherman’s main gun to be used as it swan to shore.

As detailed in Oscar Gilbert’s Marine Tank Battles in the Pacific, two platoons in each battalion combat-tested the bulky system, which proved more seaworthy than the ill-fated Sherman Duplex Drive amphibious tanks at Normandy, but not necessarily more useful as it took the Shermans five hours to swim ten miles to shore.

Gilbert further describes the T6’s role in a unique collision incident at sea:

The lead tank of the 1st Tank Battalion detachment, commanded by Sergeant D.I. Bahde, immediately ran afoul of a passing destroyer. Unable to speed up, slow down, or steer adequately, the tank plowed inexorably toward the ship, which refused to give way. The tank crashed into the side of the ship, achieving the dubious honor of being the only tank ever to ram a ship at sea.

But it wasn’t long before Marine tankers were soon heavily engaged with the nearly 100,000 Japanese soldiers and conscripted civilians defending the island.

By then the Marine tankers had perfected a “corkscrew and blow torch” in which they plastered a sector of the battlefield with main gunfire, before tanks with hull-mounted auxiliary flamethrowers rooted out the survivors.

Riflemen covered tanks from behind to ward of suicide assaults and the tankers even called down air-bursting artillery to spray shrapnel over their own turrets for added protection. Some Marine Shermans sported arrays of M2A1 anti-personnel mines on their hulls which could be remotely detonated as a last-ditch defensive measure.

Thanks to these tactics and the open terrain, Marine tank losses to close assaults were reduced to nil, contrary to the fortunes of less-experienced Army tank units.

According to Steven Zaloga in U.S. Marine Corps Tanks of World War II, a captured Japanese anti-tank officer told to his interrogators “the tank-infantry team in this operation was so successful he did not see how any defense line, however, protected, could not be penetrated…he was astounded with the volume of fire laid down by the tanks and the speed which the American tank can traverse and bring fire to bear upon Japanese anti-tank guns after the anti-tank gun opens fire.”

Yet in fact, Japanese guns and mines still inflicted considerable damage, despite the former struggling to penetrate a Sherman’s frontal armor. According to Zaloga, each Marine tank deployed to Okinawa was knocked out four times on average during the 82-day battle. And of those, a total of 51 Marine and 102 Army M4s were destroyed.

In an epic struggle for Kunishi Ridge, the 1^st Tank Battalion proved indispensable in securing the final victory after the initial assault was repelled on June 11. Just before dawn the following day, two rifle battalions from the 7^th Marine Regiment seized the ridgetop in a surprise attack. But with the coming of day, they fund their resupply and medical evacuation routes interdicted by from Japanese troops firing from inside the mountain in fortified tunnels.

The tankers came to the isolated units’ aid in a unique fashion. By stripping away two out of the five crew, the M4s could accommodate six riflemen and effectively served as very-well-armored personnel carriers. In an article, Col. Joseph Alexander describes the unusual action that followed:

No one could stand erect without getting shot, so all "transactions" had to take place via the escape hatch in the bottom of the tank's hull…a tank would lurch into the beleaguered Marine positions on Kunishi, remain buttoned up while the replacement troops slithered out of the escape hatch carrying ammo, rations, plasma, and water; then other Marines would crawl under, dragging their wounded comrades on ponchos and manhandle them into the small hole.

For those badly wounded who lacked this flexibility, the only option was the dubious privilege of riding back down to safety while lashed to a stretcher topside behind the turret. Tank drivers frequently sought to provide maximum protection to their exposed stretcher cases by backing down the entire 800-yard gauntlet. In this painstaking fashion the tankers managed to deliver 50 fresh troops and evacuate 35 wounded men…

Following a bloody second night attack, the 1^st Battalion again came to the rescue, this time delivering even more reinforcements and spiriting away 110 wounded Marines. Eventually, on June 17, L-4 Grasshoper observation planes began evacuating Marines from the ridge to an improvised airfield, relieving the burden on the tankers.

Fighting on Okinawa concluded June 21 and fortunately, Marine tankers did not see further action in World War II.

In just a few years, the Marine Corps had gone from fielding a few dozen glorified tractors with machineguns to fielding a half-dozen battalions of 30-ton medium tanks festooned with flamethrowers and applique armor and crewed by tankers studied in fighting in close cooperation with dismounted infantry to a degree seen in few armored forces before or since.

Sébastien Roblin holds a Master’s Degree in Conflict Resolution from Georgetown University and served as a university instructor for the Peace Corps in China. He has also worked in education, editing, and refugee resettlement in France and the United States.