Top Photo: Two Marines from the 2nd Battalion, 1st Marine Regiment during fighting at Wana Ridge during the Battle of Okinawa, May 1945. National Archives. NAID: 532559

The 1945 Allied amphibious invasion of Okinawa lasted from April 1 through the end of June and was the largest and deadliest operation conducted by American forces in the Pacific war. An entire field army, the Tenth, consisting of two corps—one each from the US Army and US Marine Corps—totaling eight divisions, inflicted over 100,000 casualties on the Japanese defenders. Tragically, the operation also claimed the lives of some 50,000 Okinawans, some willing or forced combatants but most simply civilians caught in the crossfire. Often overshadowed by the dropping of the atomic bombs on August 6 and 9 that contributed to Japanese capitulation, the Battle of Okinawa both led directly to the decision to use those weapons and continues to have far-reaching implications for Okinawans, Japanese–American relations, and military operations and force postures in the region. It is difficult to overstate the importance of the operation, both for the impact it had on the lives of those who participated in it, and for all who study and remember the Pacific war today.

Invading the Ryukyu Islands

The plan to seize a base in the Ryukyu Islands had long been a part of American military strategy in the western Pacific Ocean. Occupying a strategic location between the Japanese home islands and the island of Formosa (modern-day Taiwan) just off the coast of China, controlling the island chain would allow the Americans to finally sever Japan from its South Asian empire. At the same time, a base there would provide expansive air bases and secure anchorages within easy range of the southern island of Kyushu, the initial objective for the invasion of Japan. As the largest island within the Ryukyus, Okinawa became the logical destination, as the narrow, 60-mile-long island held plains suitable for airfield construction, ample room for training and rehabilitation camps, and numerous coastal indentations and anchorages protected from the Pacific’s swells where the US Navy could both stage shipping and make repairs to vessels damaged in the invasion. 

A formidable task force carves out a beachhead on Okinawa. April 13, 1945. National Archives. 

Recognizing the island’s strategic importance, Japanese commanders heavily fortified the island with two full divisions and several attached regimental and brigade-sized units, and prepared extensive defensive positions, mostly underground in the island’s porous coral and limestone. Rather than occupy vulnerable positions at the water’s edge, which would be hampered by high water tables, vulnerable to naval gunfire, and possibly overrun in any successful assault, the Japanese instead built a succession of strong defensive lines stretching across the southern end of the island. Aware that they stood little chance of success, their goal was to inflict sufficient casualties on the attackers to deter future attempts against the homeland itself. They might have succeeded too well in this objective: the staunch defense and high price in both American and Japanese lives was undoubtedly a factor in the decision by new President Harry S. Truman, who took office following President Franklin D. Roosevelt’s death on April 12, less than two weeks into the battle, to approve the use of the new atomic weapons against Japan. 

The battle for Okinawa was a joint operation in every sense of the word. Carrier-based naval aircraft provided command of the seas, even sinking the Japanese super battleship Yamato on April 7 as it sortied from the home islands on a futile mission to challenge the invasion force. The sinking of the Yamato, coupled with the Navy’s use of its own battleships—including several Pearl Harbor veterans—only in a gunfire support role placed a final nail in the coffin of the battleship as the arbiter of naval combat, ushering in the modern era of aircraft and guided missiles as the primary weapons of naval combat.

Kamikaze at Okinawa

Despite their limited naval forces, the Japanese were still able to inflict serious damage on the US Navy through the use of kamikaze (“divine wind”) aircraft. These suicide planes and their pilots became an early version of the guided missile, as the bomb-equipped aircraft were flown directly into the decks and superstructures of Allied ships. The volume of antiaircraft fire put up by the densely packed fire-support vessels in the anchorages surrounding the island increased their chances of survival, but isolated radar picket ships, set out like spokes of a wheel to provide early detection of aircraft inbound from Japan or Formosa, were extremely vulnerable and bore the brunt of these attacks. 

On April 11, a Japanese plane crashed into the USS Kidd while it was on picket duty, killing 38 sailors and wounding 55 more, nearly one-third of her crew. The remaining sailors fought both fires and subsequent attacks on their stricken vessel and saved their ship, ultimately returning it to the United States for repairs. (Today, the rebuilt and repaired ship still serves from her berth in the Mississippi River in Baton Rouge, Louisiana, as a war museum and memorial.) Throughout the campaign, the Navy lost 36 ships sunk, and another 368 were damaged, mostly smaller vessels. But the loss of life of nearly 5,000 sailors, with another 5,000 wounded, made Okinawa the Navy’s bloodiest battle of the war, greater even than its losses at Pearl Harbor.

Japanese kamikaze plane about to crash into the USS Kidd, off Okinawa, April 11, 1945. The plane hit Kidd's side, killing 38 of her crew. Photograph taken from the USS Kidd. Naval History and Heritage Command

The Land Battle for Okinawa

As vicious as the fighting was at sea, it was even worse on land. After preparatory seizures of several surrounding islets and a demonstration by the 2nd Marine Division against beaches on Okinawa’s southeast coast, the initial landings on the island’s western coast were virtually unopposed, as the Japanese remained locked in their interior fortress and only lobbed a few artillery rounds at the invasion beaches. The Army’s XXIV Corps, consisting of the veteran 7th and 96th Infantry Divisions, cut across the island’s narrow waist and quickly reached the eastern shore, isolating the Japanese defenders in the northern half of the island. As Army forces swung south to develop the Japanese defenses, the III Marine Amphibious Corps, consisting of the 1st and 6th Marine Divisions, moved north and quickly reduced all Japanese resistance on the lightly defended northern part of the island. But the Army soon found the Japanese barricaded in their defensive lines stretching across the island to the south. The first of these, called the Cactus Line, did not offer sustained opposition as it was only an outpost screening the stronger positions on Kakazu Ridge and the main defenses of the Shuri Line. 

A Marine dashes through Japanese machine gun fire while crossing a draw, called Death Valley by the men fighting there. Okinawa. May 10, 1945. National Archives

After their initial rapid progress, the American advance eventually devolved into a grinding attritional battle, as the island’s narrow width and strong defenses channeled their attacks into terrain the Japanese had mined, pre-registered for artillery, and crisscrossed with prepared fighting positions. Gains were measured in yards, often only after flamethrowers and heavy artillery barrages pulverized Japanese defensive positions, and those hard-won gains still had to be defended against Japanese counterattacks as more enemy troops emerged from their subterranean sanctuaries. The grinding attacks eventually wore down both the 7th and 96th Divisions, which were replaced in less than a month by the 27th and 77th Infantry Divisions. After wrapping up operations in the north, the two Marine divisions also took their places on the Tenth Army line, which reduced the frontage for each division but did not significantly increase the pace of forward progress. On two occasions, first on May 4 and again on May 23, Japanese troops launched major nighttime counterattacks that drew them out into the open but also struck terror in overwhelmed infantrymen who were either pushed back or overrun. It was during these attacks that Corporal Desmond Doss became the first conscientious objector to earn the Medal of Honor after repeatedly risking his life to rescue members of his unit.

In mid-May, the Okinawan monsoon season opened, adding the misery of unending deluges and deep mud to the trials of the soldiers and Marines on the line. Troops suffered food and ammunition shortages and the loss of any armored support as vehicles became bogged down in the morass. But as bad as it was for the Americans, the Japanese were also suffering irreplaceable losses and slowly giving ground. In late May, unable to use his remaining forces to maintain positions on the Shuri Line, the Japanese 32nd Army commander, Mitsuru Ushijima, instead chose to consolidate his remaining forces in a smaller perimeter at the southern tip of the island. 

The withdrawal from the Shuri Line on May 23, which both surprised and heartened the Americans, was the turning point in the battle and locked the Japanese troops—and the Okinawan civilians they forced to accompany them—into a compressed perimeter. The grinding attrition continued to take its toll. On June 22, Ushijima, realizing he could no longer hold out, committed seppuku, or ritual suicide, an example many of his surviving soldiers followed. But in a testament to American psychological warfare, and unlike many other battles of the Pacific war, some Japanese soldiers instead chose to surrender, though this could be explained by the larger numbers of Formosan, Korean, and Okinawan conscripts in the Japanese army by this point in the war. The campaign finally closed officially on July 2, just two weeks before the successful Trinity nuclear test at the Alamogordo Range in New Mexico. 

Unlike the ground and naval campaigns, little has been written about the air battle for Okinawa. Despite capturing the Yontan and Kadena airfields on the first day, the Allies were never able to gain complete control of the air around Okinawa, leading to the serious shipping losses and contributing to the stalemated battle on land. Marine Corsairs that could have been flying close support missions were instead conducting combat air patrols miles offshore. The arrival of the P-47-equipped 318th Fighter Group on Ie Shima in May helped somewhat, but the US Army Air Forces’ focus on B-29 raids against Japan siphoned fighter assets into the strategic air campaign and neglected the tactical fight on the island. As it had in Europe, the Army Air Forces believed that raids against Japanese airfields and aircraft assembly plants in the home islands could best support the operation, but the dispersed nature of Japanese aircraft and production, coupled with the large number of aircraft already hidden throughout the home islands, meant the kamikaze attacks continued almost unabated. The airfields constructed and expanded in the operation remain in use today, and Kadena Air Base is one of the largest and most important in the Pacific, but the continued American military presence on Okinawa remains a sticking point in US–Japan relations.

Lt. Richard K. Jones, OIC 3235th Sig. Ser. Det. of Hollywood, Calif., feeds children found in a tomb 50 yards from front line on Okinawa. April 23, 1945. National Archives. Digitized by Signal Corps Archive.

In addition to the estimated 100,000 Japanese defenders and as many as 50,000 indigenous Okinawans killed during the campaign, American casualties neared 50,000, with over 12,000 killed. Among them were Lieutenant General Simon B. Buckner, commander of the Tenth Army, and Ernie Pyle, the famed and beloved war correspondent. Psychological cases spiked during the battle, and the determined resistance on a relatively small, isolated island led to fears of millions dead in any invasion of the home islands themselves. Anxious to avoid this bloodletting and the loss of even more American military and Japanese civilian lives, the prospect of a quick end to the war through the use of atomic weapons became even more appealing. The brutal battle of Okinawa was the last of World War II, though the high casualty rate and miserable fighting conditions might have ironically led to a quicker, though still horrific, end to the war.