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The Battle of Okinawa (Operation Iceberg)

the only U.S. land operation on Japanese soil during World War II, the largest amphibious assault, the last major battle in the Pacific Theater, and the bloodiest campaign in the Pacific

Okinawa is the largest of the Ryuku Islands, about 60 miles long and between 2 and 18 miles wide. The Japanese had four airfields on the island, which the Americans wanted to use as take-off points for bombing raids on Japan's home islands. Being within 350 miles of Kyushu (the southernmost of Japan's major islands), American planes could reach all of Japan's industrial centers from Okinawa without having to refuel during the round trip. At the time of the battle, the island was home to about 450,000 Okinawans, who were culturally different from their Japanese overlords.

location of Okinawa
location of Okinawa

Fought between April 1 and June 22, 1945, Operation Iceberg was the first (and only) U.S. land operation on Japanese soil during World War II, as well as the largest amphibious assault and last major battle in the Pacific Theater. It was also the bloodiest campaign in the Pacific, with more than 250,000 total casualties suffered, including about one-third of the island's indigenous population.

The Combatants

U.S. land forces consisted of five divisions of the Tenth Army (7th, 27th, 77th, 81st, 96th) and two Marine divisions (1st and 6th), all commanded by Army Lieutenant-General Simon B. Buckner, Jr. With a total of 183,000 troops, the Okinawa invasion force was the largest single army under one command ever assembled during the War in the Pacific. The land forces were supported by the U.S. Fifth Fleet, which included 300 warships plus 1,139 other ships, commanded by Admiral Raymond Spruance, and by the British Pacific Fleet, which provided most of the aircraft carrier support and carried out most of the pre-invasion bombardment of Okinawa. The Marines 2nd Division was also present, but it remained as an amphibious reserve and never went ashore.

Okinawa was defended by the Japanese 32nd Army, consisting of about 77,000 troops, commanded by Lieutenant-General Mitsuru Ushijima, and by about 20,000 natives who had been conscripted and formed into the Okinawa Home Guard. The Japanese also used the island's native population as pawns in the battle, often sending out civilians to draw enemy fire while Japanese soldiers laid in waiting to ambush American troops.

The Battle

The land invasion of Okinawa was preceded by seven days of heavy naval bombardment. On March 26th, the 77th Infantry Division landed in the Kerama Islands (15 miles west of Okinawa). The island group was secured in five days, at the cost of 27 U.S. dead and 81 wounded and over 650 Japanese dead and wounded. The islands became a base from which American planes carried out bombing raids on Okinawa. Marines of the Fleet Marine Force Amphibious Reconnaissance Batallion landed without opposition on Keise (four islets eight miles west of Okinawa) on March 31st.

map showing the Battle of Okinawa
map showing the Battle of Okinawa

The Invasion

At 8:30 am on April 1st, a force consisting of the Tenth Army and the Marine 1st and 6th Divisions (about 60,000 troops) landed on the west coast of Okinawa at Hagushi. To their surprise, they encountered almost no resistance, and by 10:30 had secured of the Yontan and Kadena airfields; Nakagusuku Bay was reached within two days. The Americans had succeeded in splitting the island in two with little resistance, but taking the rest of the island would prove far more difficult and costly.

U.S. Marines going ashore at Okinawa
U.S. Marines going ashore at Okinawa

On the 6th, 400 Japanese planes launched kamikaze attacks on American invasion forces and ships. They did heavy damage to many U.S. ships, but at the cost of over 300 planes.

On the 7th, the Japanese fleet, which was sailing for Okinawa with orders to beach itself and help defend the island, was met and defeated by U.S. carrier-based planes. Virtually every ship in the fleet was either sunk or heavily damaged, including the super-battleship Yamato, a cruiser, and three destroyers. The Imperial Japanese Navy would never again pose a threat to the Allies.

Northern Campaign

The campaign to secure the northern half of Okinawa began on April 4th, when the 6th Marine Division began sweeping up Ishikawa Isthmus. The terrain was rugged and progress was relatively slow, but the Marines faced little opposition until they reached Motobu Peninsula. Most of the Japanese defenders in the north were concentrated at Yae-Take, a series of rocky pinnacles toward the western end of the peninsula, which was reached on the 14th. Fighting here was fierce, and by the time it was declared secure on the 18th at least 2,500 Japanese defenders had been killed or wounded and another 46 taken prisoner; the Americans suffered 236 killed and 1,061 wounded.

On the 16th, while the Marines were engaged at Yae-Take, the Army 77th Infantry Division launched an assault on Ie, a small island off the western end of Motobu Peninsula. Famous war correspondent Ernie Pyle was killed by machine gun fire during the fighting that ensued, as were 172 American soldiers; another 902 soldiers were wounded, and 46 were reported missing; the Japanese suffered 4,706 dead and 1,496 taken prisoner; at least 1,500 civilians also lost their lives during the fighting. The island and its airfield were declared secure on the 21st.

Southern Campaign

While the campaign to secure the northern part of Okinawa was difficult and bloody, the campaign to secure the southern part of the island was even worse. General Ushijima had chosen to concentrate the vast majority of his defenses around and south of the town of Shuri, which was naturally protected by an almost impassable line of ridges that ran from west to east and came to be known as the "Shuri Line."

As it moved south, the Army 96th Infantry Division met its first major resistance on April 4th, at "Cactus Ridge," about five miles northwest of Shuri. At the same time, the Marine 7th Division encountered heavy resistance at "The Pinnacle," about 1,000 yards southwest of Arakachi. Although both were cleared by the 8th, the "Machinato Line" between these two points would stall the American advance for almost a month. Between the 12th and 14th, the Japanese launched a series of night offensives along the American front; all were successfully repulsed, but the attacks nevertheless took their toll on the Americans. The Americans launched their own offensive, with naval bombardment and air bombings, on the 19th. The Japanese were able to escape the brunt of the assaults by taking refuge in a series of fortified caves on Kakazu Ridge, part of Shuri's outer defenses, however, and then make their own deadly assaults on American troops. A subsequent American tank assault on Kakazu Ridge resulted in the loss of 22 tanks. The Americans finally pushed through the Machinato Line on April 24.

On May 4th, Ushijima launched a counteroffensive behind American lines that included kamikaze attacks on land and sea forces. The counteroffensive failed, and, after taking time to bring in reinforcements and regroup, the Americans began their assault on the Shuri Line on the 11th. On the 13th, the 96th Infantry and 763rd Tank Batallion captured Conical Hill, east of Shuri, and the 6th Marine Division captured Sugar Loaf Hill, to the west. Fierce fighting continued until the 30th, when the 1st Marine Division finally captured Shuri Castle.

Marine placing flag on ridge above Shuri Castle
Marine placing flag on ridge above Shuri Castle

Once past the Shuri Line, the Americans made relatively quick work of the taking of Naha, the island's capital, its airfield, and the surrounding countryside. All did not go well for the Americans, however, as General Buckner was killed by artillery fire while inspecting troops at the front on June 18th, becoming the highest ranking U.S. officer killed in combat during the war; he was replaced by Marine Major-General Roy Greiger (who became the first Marine to command a numbered unit of the Army in combat), who was in turn relieved by General Joseph Stilwell.

last picture of Gen. Buckner (far right)
last picture of Gen. Buckner (far right)

The island of Okinawa was finally declared secure on June 22nd, when American forces breeched the last line of Japanese defenses and captured Mabuni, at the southern tip of the island. General Ushijima committed suicide in the closing hours of the battle, making him the highest ranking Japanese officer to die in combat during the war.

Cost and Aftermath

The Battle of Okinawa resulted in more than 250,000 total casualties, including about one-third of the island's native population. The U.S. Army and Marines suffered 7,606 dead and 32,056 wounded, while the Navy counted 4,907 dead and 4,874 wounded (the most Navy casualties ever suffered in any single operation). The U.S. also had 36 ships sunk and another 368 damaged by kamikaze attacks, and 763 planes were lost. The Japanese lost about 100,000 soldiers, pilots and sailors, but no exact count is known, and about 7,830 planes.

In 1995, the Okinawa government erected the Cornerstone of Peace Memorial in Mabuni, site of the last fighting, on which is listed all known names of those killed, American and Japanese, military and civilian, during the Battle of Okinawa (it currently contains 240,734 names).

Cornerstone of Peace Memorial
Cornerstone of Peace Memorial

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The Robinson Library >> World War II, 1939-1945

This page was last updated on 06/12/2018.