The WW2 battle of Okinawa: the bloodiest assault of the Pacific War

The US assault on Okinawa 75 years ago was the bloodiest of the Pacific War, an 83-day slog that cost 250,000 lives. Saul David describes a battle so terrible that it persuaded President Truman to reject an invasion of Japan and turn instead to the atomic bomb

The US assault on Okinawa

“Smoke and dust rose up from the shore, thousands of feet high,” wrote the Pulitzer Prize-winning war correspondent Ernie Pyle, watching from the 5th Marines’ command ship, “until finally the land was completely veiled. Bombs and strafing machine guns and roaring engines mingled with the crash of naval bombardment and seemed to drown out all existence. The ghastly concussion set up vibrations in the air – a sort of flutter – which pained and pounded the ears as though with invisible drumsticks. During all this time the waves of assault craft were forming up behind us.”

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It was 7:45am on 1 April 1945 – or ‘Love Day’, the invasion of the 70 mile-long island of Okinawa, the most southerly of Japan’s 47 prefectures. Pyle’s ship was just one of 1,300 Allied vessels, containing 183,000 combat troops, that were taking part in the greatest air-land-sea battle in history, the last major clash of the Second World War, and one that would have profound consequences for the modern world.

US Marines watch explosions during Okinawa assault
US Marines watch a barrage of phosphorus shells explode among Japanese positions. (Image by USMC-NARA)

The decision to attack Okinawa – Operation ‘Iceberg’ – had been taken by American military chiefs the previous October. Possession of Okinawa, just 400 miles south of the Japanese home islands, would allow Allied planes to bomb strategic targets on the mainland and prepare the ground for an amphibious invasion. It was the culmination of a two-pronged American advance – through New Guinea and the Philippines and, further north, through the islands of the central Pacific – that had been gathering pace since the landings on Guadalcanal in the Solomon Islands in August 1942. Now, with this second landing on Japanese soil (following Iwo Jima in February 1945), the end of the Pacific War was in sight.

Dread in the water

In one of the first assault craft to hit the beach at H-hour – 8:30am – was 22-year-old Corporal Jim Johnston from Nebraska. As they approached the shore, Johnston thought of the dead Marines he had seen in the water and on the beach during the bloody battle for the island of Peleliu the previous September, and “wondered what we would look like to the waves that would come behind us”. He approached a pillbox, anticipating the “impact of bullets ripping into my body”, but there was “no fire”. The pillbox was empty. So he and his men moved inland and, within an hour, the beachhead “was several hundred yards deep and growing by the minute”.

By nightfall, the beachhead on the west coast of Okinawa was 15,000 yards long and, in places, 5,000 yards deep. More than 60,000 men were ashore. In addition, numerous tanks and anti-aircraft units had been landed, as had all the divisional artillery and, by evening, guns were in position to support the forward troops. A captured airfield was now serviceable for emergency landings.

Okinawa was the greatest air-land-sea battle in history, the last major clash of the Second World War

The American commander, Lieutenant General Simon B Buckner Jr, was elated. “We landed practically without opposition,” he noted in his diary, “and gained more ground than we expected to for three days… The Japs have missed their best opportunity.”

Unbeknown to Buckner, who was fighting his first ever battle, the day was going entirely to plan for the Japanese commanders. Aware that their 80,000 soldiers, bolstered by around 20,000 Okinawan ‘Boeitai’ (home guard), were outgunned and outnumbered, they had chosen to concentrate the bulk of their forces behind several heavily fortified lines in the southern third of the island where, well protected in tunnels and caves, they could withstand any amount of American bombs and shells. Here several jagged lines of ridges and rocky escarpment had been turned into formidable nests of interlocking pillboxes and firing positions. All were connected by a network of caves and passageways inside the hills that allowed the defenders to move safely to each point of attack.

Stiffening opposition

Blissfully unaware of the Japanese strategy, Buckner’s men made rapid progress during the first few days of the campaign, cutting the island in two and brushing aside light enemy forces. By 4 April, Buckner’s US 10th Army held a slice of Okinawa 15 miles long and from three to ten miles wide. The beachhead included two airfields and beaches that, in the words of the official history of the Okinawa campaign, “could take immense tonnage from the cargo ships, and sufficient space for dumps and installations that were rapidly being built”.

But, as the US Army’s XXIV Corps moved south towards the main Japanese defences, the opposition stiffened. The first line was the Kakazu hill mass, which boasted formidable defensive features, including a deep moat, a hill studded with natural and man-made positions and a cluster of thick-walled buildings. A four-day assault began on 9 April, but failed to break through the storm of Japanese artillery, mortar and machine gunfire – costing the XXIV Corps almost 3,000 casualties. One veteran described the operation as a “meat-grinder” for the US troops.

When a second offensive in late April made little headway, subordinates urged Buckner to try an amphibious landing behind the Japanese defences. He refused on the grounds that the beaches in the south were too small for resupply and there was a danger that the troops would fail to break out of their beachhead.

It was a missed opportunity, and one that would have costly consequences. Buckner admitted as much to his wife when he wrote: “The Japs here seem to have the strongest position yet encountered in the Pacific, and it will be a slow tedious grind with flamethrowers, explosives placed by hand and the closest of teamwork to dislodge them without very heavy losses.”

Stumps of rotting teeth

In early May, Buckner ordered the Marines of III Amphibious Corps, which had captured the Motobu peninsula in the north, to reinforce the ‘doughboys’ of XXIV Corps in the south. The first view of the battlefield was a shock to Sergeant William Manchester of the 2/29th Marines. “It was,” he recalled, “a monstrous sight, a moonscape. Hills, ridges and cliffs rose and fell along the front like the gray stumps of rotting teeth. There was nothing green left; artillery had denuded and scarred every inch of ground. Tiny flares glowed and disappeared. Shrapnel burst with bluish white puffs. Jets of flamethrowers flickered and here and there new explosions stirred up the rubble.”

During this phase of the fighting, Private First Class Desmond Doss, a 26-year-old Seventh Day Adventist from Virginia – who had joined up as a medic to avoid the need to kill – won the Medal of Honor after rescuing at least 50 wounded comrades and then lowering them to safety down a sheer cliff known as the Maeda Escarpment. Doss’s astonishing feat was celebrated in the 2016 Mel Gibson-directed film Hacksaw Ridge.

Some of the most savage fighting was for a seemingly insignificant feature – described by one veteran as an “ugly hive” of “coral and volcanic rock, 300 yards long and 100 feet high” – dubbed Sugar Loaf Hill. The week-long battle to capture the hill cost the 6th Marine Division more than 2,600 casualties, including three battalion commanders and nine company commanders, and a further 1,200 cases of combat fatigue. With heavy rain adding to the misery, the battlefield was a hellish sight. “The scene,” wrote Eugene Sledge of 3/5th Marines, “was nothing but mud; shellfire, flooded craters with their silent, pathetic, rotting occupants; knocked-out tanks and amtracs, and discarded equipment – utter desolation… Men struggled and fought and bled in an environment so degrading I believed we had been flung into hell’s own cesspool.”

Men fought and bled in an environment so degrading I believed we had been flung into Hell's own cesspool

Determined to defend Okinawa to the last, the Japanese fought with fanatical bravery. The garrison was supported by waves of kamikaze attacks from planes, manned rockets, human torpedoes and even ships launched on suicide missions from the home islands. The planes were flown by officers of the Shimpū Tokkōtai, the Divine Wind Special Attack units, who had pledged to “crash their airplanes into enemy ships in acts of self-immolation”. Meanwhile, the one-way surface ship mission, known as Operation ‘Ten-go’, was an attempt by the superbattleship Yamato, the world’s largest, to wreak havoc among the Allied ships with its 18-inch guns before beaching itself on the shore and using its crew as naval infantry.

A kamikaze plane goes down in flames while attempting to attack USS 'Wake Island'
A kamikaze plane goes down in flames while attempting to attack USS ‘Wake Island’, 3 April 1945. (Courtesy of Naval History & Heritage Command-NARA-80-G342629)

These attacks were launched with the aim of destroying or driving off the ships of the US Fifth Fleet (including a powerful Royal Navy component) and isolating the American troops on Okinawa. But they failed – and thousands of Japanese lost their lives, including 2,500 on Yamato alone. However, they did sink 36 US ships and damage a further 368, the heaviest US naval losses of the Second World War.

Left to fight on alone, the Japanese garrison made a desperate last stand in the southern tip of the island where it had herded many civilians. The end came on 22 June 1945 when the 10th Army HQ announced that all organised resistance on Okinawa had ceased, though it would take another week to complete the mopping-up operation.

Caught in the crossfire

During the 83 days of the battle, around a quarter of a million people were killed. They included the vast majority of the 110,000 Japanese and Okinawan combatants, most of whom refused to surrender. Some 12,500 American servicemen lost their lives (out of total casualties of 76,000), making Okinawa by far the bloodiest US battle of the Pacific – and one of the costliest in the country’s history. Perhaps most tragically of all, more than 125,000 Okinawan civilians were killed (a third of the prewar population) – either caught in the crossfire or because they believed Japanese propaganda that it was better to kill themselves than be raped and murdered by the Americans. One 15-year-old Okinawan boy – who was persuaded by Japanese soldiers to kill his mother – recalled: “We tried to use rope at first, but in the end we hit her over the head with stones. I was crying as I did it and she was crying too.”

Among the notable fatalities were both field commanders – Lieutenant General Buckner was killed by a Japanese artillery shell as he observed an American attack, becoming the most senior US officer to die in the war. A Japanese vice admiral also lost his life, as did the celebrated war correspondent Ernie Pyle, who had survived north Africa, Italy and the D-Day landings only to fall to a sniper’s bullet on a small island off the north coast of Okinawa.

Truman's decision to authorise the use of the atom bomb was directly influenced by the bloodbath on Okinawa

But even more than the appalling ferocity of the fighting, it is the far-reaching consequences of Okinawa that make it one of the most significant battles in world history. On 18 June, with the Japanese resistance on Okinawa all but broken, US president Harry S Truman, in office for barely two months, met his military chiefs to discuss Japan’s unconditional surrender. The only way to achieve this, said the US Army chief of staff, George C Marshall, was to invade Japan’s home islands with a force of 750,000 men, an operation scheduled for 1 November. That would be followed up by an even bigger second invasion in the spring. Casualties were impossible to estimate, said Marshall, but given the huge number of men lost on Okinawa, and the fact that the enemy would fight even more fanatically in defence of Japan proper, it would be a “terrifying, bloody ordeal” for the servicemen involved.

Was there any alternative to a ground invasion? asked Truman. Yes, said assistant secretary of war John J McCloy. To threaten to use the newly developed atom bomb, and if the threat was ignored, to drop it on a Japanese city. “I think,” he added, “our moral position would be better if we gave them a specific warning of the bomb.”

Marines rest after a hard night's fighting, 29 May 1945
Marines rest after a hard night’s fighting, 29 May 1945. (Courtesy of Naval History & Heritage Command-NARA-127-GW-518-122511)

When challenged by others that the bomb might not go off, thus tarnishing America’s prestige, McCloy responded: “All the scientists have told us that the thing will go off. It’s just a matter of testing it out now, but they’re quite certain from reports I’ve seen that this bomb is a success.”

Truman was encouraged by this, but said no decision could be taken until they knew the bomb would work. Planning would continue for the invasion on 1 November. But everything changed on 16 July when Truman received word in Berlin, where he was attending the inter-Allied Potsdam conference with Stalin and other leaders, that the “first full scale test” of “the atomic fission bomb” in the New Mexico desert had been “successful beyond the most optimistic expectations”. The memo added: “We now had the means to insure [the war’s] speedy conclusion and save thousands of American lives.”

On hearing of the successful test in New Mexico, Winston Churchill felt that the “nightmare picture” of an invasion of Japan – which might have cost a million American and 500,000 British lives – “had vanished” and “in its place was the vision, fair and bright it seemed, of the end of the whole war in one or two violent shocks”. This “almost supernatural weapon” would give the Japanese “an excuse which would save their honour and release them from the obligation of being killed to the last fighting man”.

Soon after, Truman signed the final ultimatum to Japan, ‘the Potsdam Declaration’. It called upon Japan to agree to immediate unconditional surrender or face “prompt and utter destruction”. When Tokyo ignored the ultimatum, Truman gave the order to drop an atom bomb on Hiroshima, “an army city” and “major quartermaster depot” with warehouses full of military supplies.

A million dead

Truman’s decision to authorise the use of the atom bomb was directly influenced by the bloodbath on Okinawa. He feared that an invasion of Japan would look like “Okinawa from one end of Japan to the other”, and that it would cost the US military more than a million dead and wounded. It would also kill countless Japanese soldiers and civilians. “My object,” he wrote, “is to save as many American lives as possible but I also have a human feeling for the women and children of Japan.”

On 6 August, the US B-29 Superfortress Enola Gay dropped the first atom bomb – ‘Little Boy’ – on Hiroshima. A second bomb – ‘Fat Man’ – exploded in Nagasaki three days later. The combined dead from the bombs were 200,000 Japanese, mostly civilians – an appalling total, but less than the number killed on Okinawa, and a fraction of those who would have died if the US had invaded mainland Japan.

Such a desperate course of action was no longer necessary. Japan agreed to surrender unconditionally on 14 August, much to the delight and relief of most Americans. “When the bombs dropped,” wrote one 21-year-old American officer, “and the news began to circulate that we would not be obliged to run up the beaches near Tokyo assault-firing while being mortared and shelled, for all the fake manliness of our facades we cried with relief and joy. We were going to live. We were going to grow up to adulthood after all.”

Saul David is a military historian and broadcaster. His new book, Crucible of Hell: Okinawa – The Last Great Battle of the Second World War, will be published by William Collins on 2 April

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This article was first published in the April 2020 edition of BBC History Magazine