Military history


Amphibious Battle: Okinawa

With the fall of the Philippines and the capture of the Marianas, the war in the Pacific approached its climactic amphibious phase. Ground fighting was to continue throughout 1945 at a score of places inside or close to the Japanese ‘defensive perimeter’ of 1942; in Burma and the northern Philippines, where Manila would become a ghost city as devastated as Warsaw, fighting was to be very heavy indeed. The character of the Pacific war, however, now underwent a radical change. No longer would there be two separate and competitive American strategies, with the navy bringing overwhelming force to the landing of individual Marine divisions on tiny, remote atolls, while the army moved by shorter hooks in greater strength to seize large land masses in the Indies. Navy and army would now combine to mount large-scale amphibious operations against the outlying islands of Japan itself, involving several divisions at a time, enormous fleets and naval air forces as well as dense concentrations of embarked troops. The success of these operations would depend entirely on the combined amphibious skills of sailors, soldiers, airmen and Marines.

The Joint Chiefs of Staff had confidence in the outcome of the projected operations, of which the most important was to be the landing on Okinawa in the Ryukyu islands, only 380 miles from Kyushu, the southernmost of the large Japanese home islands. American amphibious skills were now very high but had taken time to develop – indeed, they had been developing throughout the Pacific campaign. Credit for their conception, however, belonged above all to the United States Marine Corps, which had seen the need to learn how troops could best be transferred from ship to shore twenty years before the Second World War began. The United States Marine Corps put forward the idea that transit between ship and shore must be essentially a tactical movement. The idea, so arrestingly simple, had been grasped by none of the oceanic powers before. Neither the British nor the French, though they had built great empires by projecting military through naval force, had perceived that there was more to landing troops than putting them in ships’ boats and debarking them at the water’s edge. When in 1915 they jointly mounted the great amphibious landing at Gallipoli the result was catastrophic. Hastily adapted lighters, towed to shore by steam pinnaces, were grounded under Turkish machine-guns and the soldiers on board were massacred in the water. After the First World War the US Marine Corps determined that such would not be its men’s fate. It had, admittedly, an institutional reason for wishing to make amphibious landing tactics its own particular specialism, for it entertained the fear – common to small organisations which operate between the margin of two larger ones – of being absorbed by either the army or the navy; but there was more to it than that. The Marines foresaw the danger of a Pacific war with Japan. They also saw that it could be won only with specialised methods and specialised equipment, and they set about developing both.

The architect of the Marines’ amphibious warfare doctrine was Major Earl Ellis, who in 1921 first proposed the concept of landing as a ‘ship-to-shore tactical movement’. He emphasised the need for landing troops to be covered with the heaviest available firepower as they left the ship, to debark on the run and to take up their first positions not on the beach itself but on dry ground inland. Sea and beach, in short, were to be regarded as a no man’s land. The fighting would commence in or beyond the enemy’s first defensive line well above the high-water mark. The realisation of such a concept required not only special training but also purpose-built equipment. One item was a dive-bomber, operating from a carrier but flown if possible by pilots of the Marines’ own air arm; dive-bombing was an essential means of delivering pinpoint firepower on to enemy beach strongpoints. The other was a ‘dedicated’ landing craft, with the power to cross the danger zone between ship and shore at high speed, and with the build to enable it to beach, debark and back off without waiting for tides. With time, the US Marine Corps perceived the need for two and eventually three types of landing craft. The first was a tracked amphibian or amphtrac, armoured if possible, which could actually drive out of the water and across the beach before its occupants debarked; a prototype was produced in 1924 by Walter Christie, the astonishingly creative American tank pioneer (who also fathered the T-34). The second was a larger beaching craft to carry the second wave; the successful model, the Higgins boat, was based on a civilian design built by the Higgins Company of New Orleans for use in the Mississippi delta. The third was a ship capable of beaching tanks; the sketch for the first of more than a thousand Landing Ships Tank (LST) built during the war was roughed out in a few days in November 1941 by John Niedermair of the US Navy’s Bureau of Ships. All three types could, of course, also be used to tranship the supplies which the landing troops needed once ashore.

By early 1945 the Pacific Fleet possessed all three types and many variations, in enormous numbers; the United States Coast Guard had specialised in the role of manning the Marines’ landing craft. In addition it possessed large numbers of fast ‘attack transports’, on which landing troops and craft were embarked, and which could keep pace with the destroyers and carriers of an amphibious task force. It also had numbers of dedicated command ships from which admirals and generals could jointly direct operations.

Plans for the advance to the Ryukyu islands had been laid as early as July 1944, before the Leyte landing, when Admiral Raymond Spruance, commanding the Fifth Fleet, had suggested that intermediate positions, particularly Formosa, should be bypassed and a giant stride taken to Japan’s doorstep. Admiral King, Chief of Naval Operations, at first thought the scheme over-ambitious. By September, however, when it became clear that the persistence of the war in Europe (through Hitler’s evident determination to stand on the West Wall) and MacArthur’s deep involvement in the Philippines precluded the release of more army formations, King relented. With six Marine divisions and five army divisions under his command, Nimitz now had an independent force of sufficient size for him to mount large-scale operations of his own. On 29 September 1944, therefore, King, Nimitz and Spruance, meeting at San Francisco, agreed to make Okinawa the principal target for amphibious operations in the following year. Because a main aim of the advance to the Ryukyus was to secure better air bases for the preparatory bombardment of Japan and to drive an ‘air corridor’ between the home islands and the Japanese airfields on Formosa and Luzon, it was also agreed that a subsidiary base should be seized on a smaller island nearby, which could be taken more quickly, to provide a staging post and emergency landing field for B-29s. Iwo Jima in the Bonin islands seemed the best choice. On 3 October the Joint Chiefs of Staff issued a directive for Iwo Jima to be attacked in February and Okinawa in April.

The Ten-Go plan

Meanwhile the Japanese were revising their own plans for the future conduct of the war. In September 1943 they had accepted that the 1942 defensive perimeter was untenable and had defined a new Absolute National Defence Zone, enclosing the Kuriles to the north of the home islands, the Bonins, Marianas and Carolines in the central Pacific, and western New Guinea, the East Indies and Burma in the south-west. Subsequently the American advance in 1944 had so deeply penetrated this zone that plans based on its defence were abandoned, and its architects withdrew from government; in July Tojo resigned as Prime Minister, to be replaced by the more moderate Kuniaki Koiso, though the inclusion of representatives of the war and navy ministries in the cabinet ensured that it remained under military control. By the spring of 1945 the situation had so gravely deteriorated everywhere except in China (where the Ichi-Go offensive proceeded) that imperial headquarters had to think again. It formulated a plan codenamed Ten-Go for the defence of the most vulnerable points on what remained of Japan’s defensive cordon, which included the island of Hainan between China and Indo-China, the China coast itself, Formosa and, lastly, the Ryukyus. The sub-plan for the defence of the Ryukyus, of which Okinawa was recognised to be the island most at risk, was codenamed Ten-Ichigo, and 4800 aircraft based on Formosa and the home islands were allotted to its execution. Because of the shortage of fuel, which limited the number of sorties that could be flown and severely restricted the pilots’ training hours, Ten-Ichigo was to be a new sort of offensive. The aircraft would be loaded with high explosive and would fly one-way missions to crash themselves on American ships in what the Americans would learn to call ‘kamikaze’ (‘divine wind’) suicide strikes.

The Americans had already experienced a foretaste of kamikaze tactics on the last day of the Battle of Leyte Gulf, but fortunately those suicide missions had been hastily improvised. Ten-Ichigo was more methodically prepared and was not ready for launching when the 3rd, 4th and 5th Marine Divisions assaulted Iwo Jima on 19 February. That was the only mercy granted the Americans at Iwo Jima; heavily gunned and garrisoned, honeycombed with tunnels, its bedrock of basalt covered with a deep layer of volcanic dust, the island subjected the Marines to their worst landing experience of the Pacific war. Amphtracs lost traction and ditched on the beaches, to be destroyed by salvoes from close-range artillery which three days of battleship bombardment had not destroyed; riflemen dug trenches which collapsed as soon they were deep enough to give cover; the wounded were wounded again as they lay out on the beaches awaiting evacuation. Robert Sherrod, the correspondent who had been at Tarawa and most island landings in between, thought it the worst battle he had ever seen: men died, he said, ‘with the greatest possible violence’. When Iwo Jima was finally secured on 16 March, 6821 Americans had been killed and 20,000 wounded, over a third of those who had landed; the 21,000 Japanese defenders died almost to a man.

Okinawa, the last battle

Iwo Jima provided an awful warning of what lay in store for the American divisions assigned to Okinawa – the 1st, 6th and 7th Marine, and the army’s 7th, 27th, 77th, 81st and 96th Divisions. Because of the casualties taken at Iwo Jima on the first day, it was decided to make the preparatory bombardment the heaviest yet delivered on to a Pacific island. It lasted from 24 to 31 March, and when it was over nearly 30,000 heavy-calibre shells had impacted on the landing area. On 1 April, from an armada of 1300 ships including eighteen battleships, forty carriers and 200 destroyers, the 1st and 6th Marine and 7th and 96th Divisions raced to shore in their amphtracs and Higgins boats to seize the central waist of the island, where its airfields lay, and then reduce resistance in the two halves.

Okinawa is a large island nearly eighty miles long. The American scheme for its capture was based on the supposition that, as at all but one landing so far, the Japanese would resist tenaciously at the water’s edge and then be beaten back inland, to increasingly untenable positions, by the weight of American air and naval firepower. The Japanese, anticipating American expectations, had adopted a contrary scheme for Okinawa’s defence. They were to let the Marine and army divisions land unopposed, then draw them into battle against what they regarded as impregnable defence lines within the island, meanwhile turning the weight of the kamikaze against the ships offshore. The ultimate aim was to drive the fleet away, leaving its landbound half to be destroyed at leisure.

The Japanese forces on the island numbered some 120,000 against 50,000 Americans landed on the first day – a figure that eventually rose to nearly a quarter of a million in the US Tenth Army. These Japanese troops were organised into the 24th and 62nd Divisions and together with a large number of non-divisional units formed the Thirty-Second Army, commanded by General Mitsuru Ushijima. He was more realistic than the staff officers in imperial general headquarters, since he recognised that victory on Okinawa was unattainable; nevertheless he intended to inflict the largest possible toll of casualties on the invaders, and had made preparations accordingly. The island was honeycombed with tunnels and firing positions, many of which concealed large-calibre weapons; and the fighting positions formed a series of lines which extended from the beaches where he had correctly judged the Americans would land into the high ground to the south and north.

The Americans landed virtually without loss on 1 April. The 1st and 6th Marine Divisions (whose volunteer soldiers were for the first time in the war diluted with conscripts) then turned north to clear the top of the island before joining the army’s 7th and 96th Divisions in the battle for the more mountainous south. By 6 April, as casualties mounted, both were in contact with the Machinato Line covering the southern cities of Shuri and Naha. It was on that day that the Japanese air and sea offensive against the offshore fleet began.

The Americans had already had a taste of how fiercely the Japanese intended to defend Okinawa when Task Force 58, still commanded by the resolute Admiral Mitscher, had raided the Inland Sea on 18-19 March as a preliminary to the landing. Although American carrier aircraft had destroyed some 200 Japanese aircraft, the task force had also suffered heavily itself. The carrier Wasp was badly damaged by a kamikaze and only saved by rapid firefighting, a technique at which the American now excelled all other navies. Another carrier, Franklin, was hit by two bombs which almost incinerated the ship; 724 of her crew died, the highest fatal casualty toll suffered by any surviving American ship in the Pacific war.

On 6 April kamikazes attacked in dense waves; at the same time, far to the north, Japan’s last operational surface force, the giant battleship Yamato escorted by a cruiser and eight destroyers set sail from Japan. Yamato had taken on board the last 2500 tons of fuel available at her Japanese home port to make the one-way trip. Her mission was to penetrate the screen around the Okinawa beaches and inflict unacceptable damage on the amphibious force. She was detected long before she got within range, however, and at noon on 7 April was taken under attack by 280 aircraft of Task Force 58. Between noon and two o’clock she suffered six torpedo hits, lost speed and steering, became a sitting duck to successive waves of American aircraft and at 2.23 pm rolled over and sank with almost all the 2300 sailors on board. Her cruiser and four of her seven destroyer escorts were also sunk. This ‘Special Surface Attack Force’ had launched the Imperial Japanese Navy’s last sortie of the war.

The kamikazes proved far more difficult to repel. About 900 aircraft, of which a third were on suicide missions, attacked the amphibious fleet on 6 April and by the end of the day, although 108 were shot down, three destroyers, two ammunition ships and an LST had been sunk. The attacks were repeated on 7 April when a battleship, a carrier and two destroyers were all hit by kamikaze strikes. The American response was to thicken the screen of radar-picket destroyers, lying off Okinawa up to ranges of 95 miles, which gave early warning of attacks. There were soon sixteen on station, eleven of which lay in the semicircle between the north-eastern and south-western azimuths, nearest Japan and Formosa. As the British task force at the Falklands was to rediscover forty years later, however, a screen of radar pickets may give the large units of a fleet early warning of attack; but its mission is a sacrificial one, for the incoming enemy strikes readily choose its ships as targets. That was to be the American destroyers’ fate. Between 6 April and 29 July fourteen American destroyers were sunk by suicide pilots, together with another seventeen LSTs, ammunition ships and assorted large landing craft lying within the screen. Over 5000 American sailors died as a result of the Okinawa kamikaze campaign – the heaviest toll the US Navy had suffered in any episode of the war, including Pearl Harbor.

Between 6 April and 10 June, besides many smaller missions the kamikaze corps mounted ten mass attacks by 50-300 aircraft, which damaged battleships and aircraft carriers as well as destroyers; the venerable Enterprise and the newer carriers HancockandBunker Hill were all kamikaze victims, and Bunker Hill, Spruance’s flagship, lost 396 of her crew killed. American carriers, which were horizontally armoured above the engine room but below the flight deck, burned all too easily when a kamikaze landed aboard. A principal advantage of the four British carriers of Task Force 57, which joined the American force off Okinawa in March, was that they were armoured on their flight decks as a precaution against the shellfire likely to be encountered in narrower European waters, and therefore survived kamikaze strikes without serious damage.

Ultimately the kamikaze attacks could not go on, for the Japanese began to run out of both pilots and aircraft; the number of raids was heavier in April than in May and far heavier in May than in June, when only four ships were sunk. However, the pickets were bound to remain in place – and so expose themselves to damage or sinking, at almost unbearable cost to their crews’ nerves – as long as the army and Marines battled ashore. As the campaign protracted, Nimitz grew increasingly impatient with the Tenth Army commander, General Simon Bolivar Buckner, complaining that he lost ‘a ship and a half a day’ at the pace at which the front was moving. Buckner, son of the general who had fought Ulysses S. Grant in the American Civil War in 1862, resolutely defended his methodical tactics. Successive ridge lines imposed delay on every offensive mounted. The lines were washed by constant rain, which bogged tanks trying to give support, and they were fanatically defended by Japanese who, whether trained infantrymen or wholly inexperienced naval shore personnel, fought literally to the death. Not until the end of June did resistance cease, and some 4000 Japanese surrendered in the last days. All the Japanese senior officers, including Ushijima, committed ritual suicide, as did many of their subordinates and some civilian Japanese. The Okinawan population, 450,000 strong at the outset, had suffered terribly; at least 70,000 and perhaps as many as 160,000 died in the course of the fighting. Thousands took refuge in the island’s numerous caves, which the garrison subsequently occupied as strongpoints, and were killed when the American infantry attacked them with flamethrowers and high explosive.

For the fighting troops Okinawa had been the grimmest of all Pacific battles. The American army divisions lost 4000 killed, the Marine Corps 2938; 763 aircraft were destroyed and 38 ships sunk. The Japanese lost 16 ships and an almost incredible total of 7800 aircraft, over a thousand in kamikaze missions. The Japanese servicemen on the island – shore-based sailors as well as front-line riflemen, clerks, cooks, Okinawan labour conscripts – found ways of dying almost to the last man. The American total of prisoners, including men too badly wounded to commit suicide, was 7400; all the others, 110,000 in number, died refusing to surrender.

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