The Battle of Okinawa (Japanese: 沖縄戦, Hepburn: Okinawa-sen), codenamed Operation Iceberg, was a major battle of the Pacific War fought on the island of Okinawa by the United States Army and United States Marine Corps forces against the Imperial Japanese Army. The initial invasion of Okinawa on 1 April 1945 was the largest amphibious assault in the Pacific Theater of World War II. The Kerama Islands surrounding Okinawa were preemptively captured on 26 March 1945 by the U.S. Army 77th Infantry Division. The 82-day battle on Okinawa lasted from 1 April 1945 until 22 June 1945. After a long campaign of island hopping, the Allies were planning to use Kadena Air Base on the island as a staging point for Operation Downfall, the planned invasion of the Japanese home islands, 340 mi (550 km) away.
The United States created the Tenth Army, a cross-branch force consisting of the U.S. Army 7th, 27th, 77th and 96th Infantry Divisions with the 1st, 2nd, and 6th Marine Divisions, to secure the island. The Tenth Army was unique because it had its own Tactical Air Force (joint Army-Marine command) and was supported by combined naval and amphibious forces. Opposing the Allied forces on the ground was the Japanese Lieutenant General Mitsuru Ushijima's Thirty-Second Army, a mixed force consisting of regular army troops, naval infantry and conscripted local Okinawans. There were about 100,000 Japanese troops on Okinawa at the onset of the invasion. The battle was the longest sustained carrier campaign of the Second World War.
The battle has been referred to as the "typhoon of steel" (鉄の暴風, tetsu no bōfū). The nicknames refer to the ferocity of the fighting, the intensity of Japanese kamikaze attacks and the significant volume of Allied vessels and armored vehicles that assaulted the island. The battle was the bloodiest and fiercest in the Pacific Ocean Theatre, with some 50,000 Allied and around 100,000 Japanese casualties, also including local Okinawans conscripted into the Japanese Army. According to local authorities, at least 149,425 Okinawan people were killed, died by coerced suicide or went missing.
In the naval operations surrounding the battle, both sides lost a considerable number of ships and aircraft, including the Japanese battleship Yamato. After the battle, Okinawa provided the victorious Allies with a fleet anchorage, troop staging areas, and airfields in close proximity to Japan as they planned to invade the Japanese home islands.
Order of battle
Allied
In all, the US Army had over 103,000 soldiers (of these, 38,000+ were non-divisional artillery, combat support and HQ troops, with another 9,000 service troops), over 88,000 Marines and 18,000 Navy personnel (mostly Seabees and medical personnel). At the start of the Battle of Okinawa, the US Tenth Army had 182,821 personnel under its command. It was planned that Lieutenant General Simon Bolivar Buckner Jr. would report to Vice Admiral Richmond K. Turner until the amphibious phase was completed, after which he would report directly to Admiral Raymond A. Spruance. Total aircraft provided by the US Navy, Marine and Army Air Force exceeded 3,000 over the course of the battle, including fighters, attack aircraft, scout planes, bombers and dive-bombers. The invasion was supported by a fleet consisting of 18 battleships, 27 cruisers, 177 destroyers/destroyer escorts, 39 aircraft carriers (11 fleet carriers, 6 light carriers and 22 escort carriers) and various support and troop transport ships.
The British naval contingent accompanied 251 British naval aircraft and included a British Commonwealth fleet with Australian, New Zealand and Canadian ships and personnel.
Japanese
The Japanese land campaign (mainly defensive) was conducted by the 67,000-strong (77,000 according to some sources) regular 32nd Army and some 9,000 Imperial Japanese Navy troops at Oroku Naval Base (only a few hundred of whom had been trained and equipped for ground combat), supported by 39,000 drafted local Ryukyuan people (including 24,000 hastily drafted rear militia called Boeitai and 15,000 non-uniformed laborers). The Japanese had used kamikaze tactics since the Battle of Leyte Gulf, but now for the first time they became a major institutionalized aspect of the Japanese defensive strategy. Between the American landing on 1 April and 25 May, seven major kamikaze attacks were attempted, involving more than 1,500 planes.
The 32nd Army initially consisted of the 9th, 24th and 62nd Divisions and the 44th Independent Mixed Brigade. The 9th Division was moved to Taiwan before the invasion, resulting in shuffling of Japanese defensive plans. Primary resistance was to be led in the south by Lieutenant General Mitsuru Ushijima, his chief of staff, Lieutenant General Isamu Chō and his chief of operations, Colonel Hiromichi Yahara. Yahara advocated a defensive strategy, whilst Chō advocated an offensive one.
In the north, Colonel Takehiko Udo was in command. The naval troops were led by Rear Admiral Minoru Ōta. They expected the Americans to land 6–10 divisions against the Japanese garrison of two and a half divisions. The staff calculated that superior quality and numbers of weapons gave each US division five or six times the firepower of a Japanese division. To this, would be added the Americans' abundant naval and air firepower.
Japanese use of children
On Okinawa, the Imperial Japanese Army mobilized 1,780 schoolboys aged 14–17 years into front line service as an Iron and Blood Imperial Corps (Japanese: 鉄血勤皇隊, romanized: Tekketsu Kinnōtai), while female Himeyuri students were organized into a nursing unit. This mobilization was conducted by an ordinance of the Ministry of the Army, not by law. The ordinances mobilized the students as volunteer soldiers for form's sake; in reality, the military authorities ordered schools to force almost all students to "volunteer" as soldiers; sometimes they counterfeited the necessary documents. About half of the Tekketsu Kinnōtai were killed, including in suicide bomb attacks against tanks and in guerrilla operations.
Among the 21 male and female secondary schools that made up these student corps, 2,000 students died on the battlefield. Even with the female students acting mainly as nurses to Japanese soldiers, they were still exposed to the harsh conditions of war.
Naval battle
There was a hypnotic fascination to the sight so alien to our Western philosophy. We watched each plunging kamikaze with the detached horror of one witnessing a terrible spectacle rather than as the intended victim. We forgot self for the moment as we groped hopelessly for the thought of that other man up there.
The US Navy's Task Force 58, deployed to the east of Okinawa with a picket group of 6 to 8 destroyers, kept 13 carriers (7 fleet carriers and 6 light carriers) on duty from 23 March to 27 April and a smaller number thereafter. Until 27 April, a minimum of 14 and up to 18 escort carriers were in the area at all times. Until 20 April, British Task Force 57, with 4 large and 6 escort carriers, remained off the Sakishima Islands to protect the southern flank.
The protracted length of the campaign under stressful conditions forced Admiral Chester W. Nimitz to take the unprecedented step of relieving the principal naval commanders to rest and recuperate. Following the practice of changing the fleet designation with the change of commanders, US naval forces began the campaign as the US 5th Fleet under Admiral Spruance, but ended it as the 3rd Fleet under Admiral Halsey.
Japanese air opposition had been relatively light during the first few days after the landings. However, on 6 April the expected air reaction began with an attack by some 400 Japanese planes from Kyushu.
Similar air attacks continued through April. From 26 March to 30 April, 20 American ships were sunk and 157 damaged by enemy action. By 30 April, the Japanese had lost more than 1,100 planes to Allied naval forces alone.
Between 6 April and 22 June, the Japanese flew 1,465 kamikaze aircraft in large-scale attacks from Kyushu, 185 individual kamikaze sorties from Kyushu, and 250 individual kamikaze sorties from Taiwan, then called Formosa. While US intelligence estimated there were 89 planes on Formosa, the Japanese actually had about 700, dismantled or well camouflaged and dispersed into scattered villages and towns; the US Fifth Air Force disputed Navy claims of kamikaze coming from Formosa.
The ships lost were smaller vessels, particularly the destroyers of the radar pickets, as well as destroyer escorts and landing ships. While no major Allied warship was lost, several fleet carriers were severely damaged. Land-based Shin'yō-class suicide motorboats were also used in the Japanese suicide attacks, although Ushijima had disbanded the majority of the suicide boat battalions before the battle because of expected low effectiveness against a superior enemy. The boat crews were re-formed into three additional infantry battalions.
Operation Ten-Go
Operation Kikusui I (菊水作戦, Kikusui Sakusen 1; Operation Chrysanthemum Water 1), best known as Operation Ten-Go (天号作戦, Ten-Gō Sakusen), literally Operation Heaven and in Japanese sources as the Battle off Cape Bono (坊ノ岬沖海戦, Bōno Misaki Oki-Kaisen) was the last major Japanese naval operation in the Pacific Theater of World War II. In April 1945, the Japanese battleship Yamato, the largest battleship in the world, and nine other Japanese warships, embarked from Japan for a suicide attack on Allied forces engaged in the Battle of Okinawa. The Japanese force was attacked by U.S. carrier-borne aircraft before it could reach Okinawa; Yamato and five other Japanese warships were sunk, while 10 American aircraft were shot down. Several ships in the U.S. carrier task force suffered moderate damage from aerial kamikaze attacks, while 100 Japanese planes were lost. Operation Kikusui I, best known as Operation Ten-Go, refers specifically to Yamato's sortie, while Operation Kikusui refers specifically to all Japanese kamikaze operations during the entire Okinawa campaign.
British Pacific Fleet
The British Pacific Fleet, taking part as Task Force 57, was assigned the task of neutralizing the Japanese airfields in the Sakishima Islands, which it did successfully from 26 March to 10 April. On 10 April its attention was shifted to airfields in northern Formosa. The force withdrew to San Pedro Bay on 23 April. On 1 May, the British Pacific Fleet returned to action, subduing the airfields as before, this time with naval bombardment as well as aircraft (they only used aircraft during their first mission of destroying airfields in the Sakishima Islands). Several kamikaze attacks caused significant damage, but as the Royal Navy carriers had armored flight decks, they experienced only a brief interruption to their force's operations.
Land battle
The land battle took place over about 81 days beginning on 1 April 1945. The first Americans ashore were soldiers of the 77th Infantry Division who landed in the Kerama Islands, 15 mi (24 km) west of Okinawa on 26 March. Subsidiary landings followed, and the Kerama group was secured over the next five days. In these preliminary operations, the 77th Infantry Division suffered 27 dead and 81 wounded, while the Japanese dead and captured numbered over 650. On 28 March 1945, 394 civilians on Tokashiki island were forced by Japanese soldiers to kill themselves after the landing of US troops. The operation provided a protected anchorage for the fleet and eliminated the threat from suicide boats.
On 31 March, Marines of the Amphibious Reconnaissance Battalion landed without opposition on Keise Shima, four islets just 8 mi (13 km) west of the Okinawan capital of Naha. A group of 155 mm (6.1 in) "Long Tom" artillery pieces went ashore on the islets to cover operations on Okinawa.
Northern Okinawa
The main landing was made by the XXIV Corps and the III Amphibious Corps on the Hagushi beaches on the western coast of Okinawa on 1 April. The 2nd Marine Division conducted a demonstration off the Minatoga beaches on the southeastern coast to deceive the Japanese about American intentions and delay movement of reserves from there.
Tenth Army swept across the south-central part of the island with relative ease, capturing the Kadena and the Yomitan airbases within hours of the landing. In light of the weak opposition, General Buckner decided to proceed immediately with Phase II of his plan, the seizure of northern Okinawa. The 6th Marine Division headed up the Ishikawa Isthmus and by 7 April had sealed off the Motobu Peninsula.
Six days later on 13 April, the 2nd Battalion, 22nd Marine Regiment, reached Hedo Point at the northernmost tip of the island. By this point, the bulk of the Japanese forces in the north (codenamed Udo Force) were cornered on the Motobu Peninsula. The terrain was mountainous and wooded, with the Japanese defenses concentrated on Mount Yaedake, a twisted mass of rocky ridges and ravines on the center of the peninsula. There was heavy fighting before the Marines finally cleared Yaedake on 18 April. However, this was not the end of ground combat in northern Okinawa. On 24 May, the Japanese mounted Operation Gi-gou: a company of Giretsu Kuteitai commandos were airlifted in a suicide attack on Yomitan. They destroyed 70,000 US gallons (260,000 L) of fuel and nine planes before being killed by the defenders, who lost two men.
Meanwhile, the 77th Infantry Division assaulted Ie Shima, a small island off the western end of the peninsula, on 16 April. In addition to conventional hazards, the 77th Infantry Division encountered kamikaze attacks and even local women armed with spears. There was heavy fighting before the area was declared secured on 21 April and became another airbase for operations against Japan.