World War II: Battle of Okinawa

The Battle of Okinawa was one of the largest and costliest military actions during World War II (1939–1945) and lasted between April 1 and June 22, 1945.

Forces & Commanders

Allies

• Fleet Admiral Chester Nimitz
• Admiral Raymond Spruance
• Admiral Sir Bruce Fraser
• Lieutenant General Simon B. Buckner, Jr.
• Lieutenant General Roy Geiger
• General Joseph Stilwell
• 183,000 men

Japanese

• General Mitsuru Ushijima
• Lieutenant General Isamu Cho
• Vice Admiral Minoru Ota
• 100,000+ men

Background

Having "island-hopped" across the Pacific, Allied forces sought to capture an island near Japan to serve as a base for air operations in support of the proposed invasion of the Japanese home islands. Assessing their options, the Allies decided to land on Okinawa in the Ryukyu Islands. Dubbed Operation Iceberg, planning began with Lieutenant General Simon B. Buckner's 10th Army tasked with taking the island. The operation was scheduled to move forward following the conclusion of fighting on Iwo Jima which had been invaded in February 1945. To support the invasion at sea, Admiral Chester Nimitz assigned Admiral Raymond Spruance's U.S. 5th Fleet (Map). This included the carriers Vice Admiral Marc A. Mitscher's Fast Carrier Task Force (Task Force 58).

Allied Forces

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For the coming campaign, Buckner possessed nearly 200,000 men. These were contained in Major General Roy Geiger's III Amphibious Corps (1st and 6th Marine Divisions) and Major General John Hodge's XXIV Corps (7th and 96th Infantry Divisions). In addition, Buckner controlled the 27th and 77th Infantry Divisions, as well as the 2nd Marine Division. Having effectively eliminated the bulk of the Japanese surface fleet at engagements such as the Battle of the Philippine Sea and the Battle of Leyte Gulf, Spruance's 5th Fleet was largely unopposed at sea. As part of his command, he possessed Admiral Sir Bruce Fraser's British Pacific Fleet (BPF/Task Force 57). Featuring armored flight decks, the BPF's carriers proved more resistant to damage from Japanese kamikazes and were tasked with providing cover for the invasion force as well as striking enemy airfields in the Sakishima Islands.

Japanese Forces

The defense of Okinawa was initially entrusted to General Mitsuru Ushijima's 32nd Army which consisted of the 9th, 24th, and 62nd Divisions and the 44th Independent Mixed Brigade. In the weeks before the American invasion, the 9th Division was ordered to Formosa forcing Ushijima to alter his defensive plans. Numbering between 67,000 and 77,000 men, his command was further supported by Rear Admiral Minoru Ota's 9,000 Imperial Japanese Navy troops at Oroku. To augment his forces further, Ushijima drafted nearly 40,000 civilians to serve as reserve militia and rear-echelon laborers. In planning his strategy, Ushijima intended to mount his primary defense in the southern part of the island and entrusted fighting at the northern end to Colonel Takehido Udo. Additionally, plans were made to employ large-scale kamikaze tactics against the Allied invasion fleet.

Campaign at Sea

The naval campaign against Okinawa began in late March 1945, as the carriers of the BPF began striking Japanese airfields in the Sakishima Islands. To the east of Okinawa, Mitscher's carrier provided cover from kamikazes approaching from Kyushu. Japanese air attacks proved light the first several days of the campaign but increased on April 6 when a force of 400 aircraft attempted to attack the fleet. The high point of the naval campaign came on April 7 when the Japanese launched Operation Ten-Go. This saw them attempt to run the battleship Yamato through the Allied fleet with the goal of beaching it on Okinawa for use a shore battery. Intercepted by Allied aircraft, Yamato and its escorts were immediately attacked. Struck by multiple waves of torpedo bombers and dive bombers from Mitscher's carriers, the battleship was sunk that afternoon.

As the land battle progressed, Allied naval vessels remained in the area and were subjected to a relentless succession of kamikaze attacks. Flying around 1,900 kamikaze missions, the Japanese sunk 36 Allied ships, mostly amphibious vessels and destroyers. An additional 368 were damaged. As a result of these attacks, 4,907 sailors were killed and 4,874 were wounded. Due to the protracted and exhausting nature of the campaign, Nimitz took the drastic step of relieving his principal commanders at Okinawa to allow them to rest and recuperate. As result, Spruance was relieved by Admiral William Halsey in late May and Allied naval forces were re-designated the 3rd Fleet.

Going Ashore

Initial U.S. landings began on March 26 when elements of the 77th Infantry Division captured the Kerama Islands to the west of Okinawa. On March 31, Marines occupied Keise Shima. Only eight miles from Okinawa, the Marines quickly emplaced artillery on these islets to support future operations. The main assault moved forward against the Hagushi beaches on the west coast of Okinawa on April 1. This was supported by a feint against the Minatoga beaches on the southeast coast by the 2nd Marine Division. Coming ashore, Geiger and Hodge's men quickly swept across the south-central part of the island capturing the Kadena and Yomitan airfields (Map).

Having encountered light resistance, Buckner ordered the 6th Marine Division to begin clearing the northern part of the island. Proceeding up the Ishikawa Isthmus, they battled through rough terrain before encountering the main Japanese defenses on the Motobu Peninsula. Centered on the ridges of Yae-Take, the Japanese mounted a tenacious defense before being overcome on April 18. Two days earlier, the 77th Infantry Division landed on the island of Ie Shima offshore. In five days of fighting, they secured the island and its airfield. During this brief campaign, famed war correspondent Ernie Pyle was killed by Japanese machine gun fire.

Grinding South

Though fighting in the northern part of the island was concluded in fairly rapid fashion, the southern part proved a different story. Though he did not expect to defeat the Allies, Ushijima sought to make their victory as costly as possible. To this end, he had constructed elaborate systems of fortifications in the rugged terrain of southern Okinawa. Pushing south, Allied troops fought a bitter battle to capture Cactus Ridge on April 8, before moving against Kakazu Ridge. Forming part of Ushijima's Machinato Line, the ridge was a formidable obstacle and an initial American assault was repulsed (Map).

Counterattacking, Ushijima sent his men forward on the nights of April 12 and 14, but was turned back both times. Reinforced by the 27th Infantry Division, Hodge launched a massive offensive on April 19 backed by the largest artillery bombardment (324 guns) employed during the island-hopping campaign. In five days of brutal fighting, U.S. troops forced the Japanese to abandon the Machinato Line and fall back to a new line in front of Shuri. As much of the fighting in the south had been conducted by Hodge's men, Geiger's divisions entered the fray in early May. On May 4, Ushijima again counterattacked, but heavy losses caused him to halt his efforts the next day.

Achieving Victory

Making skillful use of caves, fortifications, and the terrain, the Japanese clung to the Shuri Line limiting Allied gains and inflicting high losses. Much of the fighting centered on heights known as Sugar Loaf and Conical Hill. In heavy fighting between May 11 and 21, the 96th Infantry Division succeeded in taking the latter and flanking the Japanese position. Taking Shuri, Buckner pursued the retreating Japanese but was hampered by heavy monsoon rains. Assuming a new position on the Kiyan Peninsula, Ushijima prepared to make his last stand. While troops eliminated the IJN forces at Oroku, Buckner pushed south against the new Japanese lines. By June 14, his men had begun to breach Ushijima's final line along the Yaeju Dake Escarpment.

Compressing the enemy into three pockets, Buckner sought to eliminate enemy resistance. On June 18, he was killed by enemy artillery while at the front. Command on the island passed to Geiger who became the only Marine to oversee large formations of the U.S. Army during the conflict. Five days later, he turned command over to General Joseph Stilwell.  A veteran of the fighting in China, Stilwell saw the campaign through until its finish. On June 21, the island was declared secure, though fighting lasted another week as the last Japanese forces were mopped up. Defeated, Ushijima committed hara-kiri on June 22.

Aftermath

One of the longest and costliest battles of the Pacific Theater, Okinawa saw American forces sustain 49,151 casualties (12,520 killed), while the Japanese incurred 117,472 (110,071 killed). In addition, 142,058 civilians became casualties. Though effectively reduced to a wasteland, Okinawa quickly became a key military asset for the Allies as it provided a key fleet anchorage and troop staging areas. In addition, it gave the Allies airfields that were only 350 miles from Japan.

Selected Sources

• U.S. Army: Okinawa - The Last Battle
• HistoryNet: Battle of Okinawa
• Global Security: Battle of Okinawa
• U.S. Army: Okinawa - The Last Battle