Okinawa: The Final Battle

Operation ICEBERG, the American invasion of the Ryukyu island chain, was the last major battle of World War II and contained some of the most seasoned veterans of the American fighting men. Even so, the battle for Okinawa lasted three months and saw the heaviest casualties of the Pacific War. The invasion was a joint operation, containing Navy, Marine, and Army troops, and all three branches felt the cost of the war. The price of Operation ICEBERG was so high that the new President and the Joint Chiefs of Staff had to reconsider their plan to invade the Japanese Home Islands. Okinawa became a pivotal battle, as the lessons learned informed the decisions which would bring about the end of the war.

Okinawa was the last island to conquer before the Americans trained their sights on invading Japan itself, and the Japanese military planners knew it. Lieutenant General Mitsuru Ushijima, commander of the Japanese 32^nd Imperial Army, also knew that the Japanese could not hope to keep the island out of American hands. Instead, his goal was to make the Americans pay for every yard of soil with their own blood. The strategy of attrition had already been used to great effect on Peleliu and Iwo Jima, and although both of those islands had also been taken by U.S. forces, it had cost them dearly. Ushijima hoped that the price of taking Okinawa would be so high that the Americans would reconsider their obvious end goal of invading Japan itself.

The defenses on Okinawa turned the hilly landscape into a death trap on every ridge. Because of the strategic importance of the island and its proximity to Japan, Ushijima’s forces had spent several months constructing their defensive network both on and in the island. The Japanese dug into the hills and created complexes and tunnels, much like Kuribayashi’s forces had on Iwo Jima. They focused on the southern half of the island, the more heavily populated end, due to manpower concerns and the necessity of creating strongpoints from which to mow down the invaders. On Okinawa, defenses were designed to defend one slope from the surrounding hills. The bunkers and pillboxes were hidden in caves or carved-out tunnels to protect them from naval bombardment. The Americans would have to clear every hill and cave to eliminate the defenders, losing a great number of men in the process.The U.S. Navy spent weeks assembling the amphibious assault force for Okinawa and conducting preinvasion bombardment to soften the island’s defenses. The Fifth Fleet under Admiral Raymond Spruance, accompanied by Admiral Marc Mitscher’s Task Force 58, eventually contained well over 1,500 ships and 350,000 personnel, all ready to support and protect the invasion of the Ryukyus. The preinvasion bombardment of Okinawa was so heavy that it was described as a “typhoon of steel.” Even so, the artillery hardly touched the underground Japanese fortifications. The U.S. carriers also unleashed air strikes, and the fleet conducted minesweeping operations to clear the way for the landing craft.

With these preparations to pave the way, U.S. Army and Marines landed on Okinawa on L-Day, 1 April 1945. It was both Easter Sunday and April Fool’s Day, and to some, the virtually uncontested landing on the island felt like either a blessing or a joke. For years, the Japanese counterattacks had targeted the landing invaders, and both Peleliu and Iwo Jima had taught the men to expect brutal fighting on the beaches. The lack of response from the defenders was eerie to many veteran Americans, who were bracing themselves for a bloodbath once they landed. Yet the invasion forces not only landed on the beaches without issue, but they were able to cross the beaches walking upright, something entirely unheard of in the rest of the Pacific War. Admiral Spruance famously messaged Admiral Chester Nimitz about the situation on Okinawa, “I may be crazy, but it looks like the Japanese have quit the war, at least in this sector,” to which Nimitz responded “Delete all after ‘crazy’.”

By the end of L-Day, 60,000 troops and their accompanying supplies and war machines had landed on Okinawa, and still encountered no resistance. In the next few days, American forces pushed across the island, taking the opposite coast as well as the airfields of Yontan and Kadena near the landing beaches. Within four days of the initial landings, the ground forces on Okinawa had accomplished what was expected to take them around three weeks. Japanese defenders still remained scarce, leaving the Americans to wonder where they were all hiding. They did not have to wait long for the answers.

After making it to the opposite side of the island, the Marine and Army units split up. The 6^th Marines turned towards the north up towards the Motobu Peninsula, where they found the Yaeju-Dake hills thickly entrenched with Japanese defenders. After about two weeks of fighting, the Marines managed to secure the northern half of the island on 18 April with under 1,000 total casualties. The Army’s 77^th Division was tasked with taking the nearby island of Ie Shima, which would become an American fighter base. The rest of the Army moved south, directly into the maze of hills, ridges, and caves that the Japanese had turned into their own nightmarish fortifications.

The Japanese first defensive point, the Machinato Line, made up for the peace of the first few days with ferocious counterattacks against American assault. Every ridge, cave, and cliff was packed with Japanese defenders determined to hold their positions for as long as possible. The same hidden defense strategy that the Marines encountered on Iwo Jima played out with the 7^th and 96^th Infantry Divisions on Okinawa as men attacked and were mowed down by concealed artillery and enemy soldiers. Some fortifications had multiple underground levels and tunnels connecting them to nearby positions, allowing for Japanese troops to move about to offer reinforcements or additional fire to weakened areas. Since practically every single defender would need to be eliminated before a position could be secured, the Army found the task of slow attrition of enemy forces brutal and unforgiving. The Americans managed to inflict even more casualties than they suffered, but with the Japanese so well-hidden, there was very little to show for it.

Japanese defenses slowed the American advance considerably, despite the rapid pace of the initial assault on the island. Army troops in the south were engaged in constant battle with little sleep and next to no progress in some areas. They assaulted points such as Kakazu Ridge and Tombstone Ridge for days, charging up the slope only to be repelled by Japanese artillery on the reverse side. The Army finally broke through the Machinato Line on 20 April after weeks of bloody fighting. Admiral Nimitz complained to General Simon Bolivar Buckner, Jr., the overall commander of the American ground forces for Okinawa, that the Navy was losing “about a ship and a half a day” as they remained tethered to the island to support the ground troops. Buckner ordered the 1^st and 6^th Marine Divisions to relieve the exhausted Army in the south, and the reinforcements helped to move the Americans along.

The U.S. Fifth Fleet, anchored offshore, encountered its own troubles. Japanese suicide planes swarmed the ships in the largest kamikaze attack of the Pacific War. U.S. radar picket stations, the navy early warning systems for air attacks, often fell prey to swarms of kamikaze en route to the island. The destroyer USS Hugh W. Hadley was credited with downing an incredible 23 planes in 1 hour, 40 minutes while serving as a picket boat off Okinawa. The Hadley survived, but many other ships of the Fifth Fleet were not so lucky. Nearly 40% of the American deaths from Okinawa were Navy personnel killed by kamikazes, sinking more than 25 ships and damaging well over 150 more.

The Japanese were not the only difficulty the Americans had to contend with. The last possible day for L-Day was set at 1 April due to the approaching monsoon season, and as progress stalled on the island, the weather worsened. Torrential rain began to fall and continued nonstop for weeks. The landscape turned to endless quagmires and mud made its way into everything from the uniforms to equipment to wounds, even into sealed ration packages. Corpses which had been previously buried were unearthed in the rivers of muck that covered the island. Vehicles stalled, boots were sucked off, and any advance was stopped cold. Yet the island still had to be taken, and soldiers and Marines struggled in meat-grinder battles to claim positions like the Shuri Line, Wana Draw, and Hacksaw Ridge. The psychological effects of the mud, fighting, and sleep deprivation took their toll, and battle fatigue comprised most of the noncombat casualties on Okinawa.

Despite the fierce defenses and vicious counterattacks from the Japanese, Ushijima and his military commanders knew that they could not keep the island. No reinforcements arrived on Okinawa, as the Imperial Japanese Headquarters began reserving men and resources for the defense of the Home Islands. The Japanese army conscripted tens of thousands of native Okinawans to combat the Americans, including using women and children in suicide attacks and as human shields. The civilians were told again and again by Japanese propaganda that the Americans would rape, torture, and kill anyone they could capture, so many Okinawans who did not die in the battle chose to commit suicide rather than be taken alive. As a result, Okinawan deaths made up the majority of the battle’s casualties, with up to 150,000 of the island’s approximately 500,000 inhabitants killed during the campaign.

The battle for Okinawa finally ended on 22 June 1945 as General Ushijima and his chief of staff General Cho committed hara-kiri, or ritual suicide. The battle had lasted 82 days and exacted roughly 250,000 casualties from Americans, Japanese, and Okinawans. American military planners were shocked and appalled at the heavy loss of life on all sides. Yet the invasion of the Home Islands, with many more civilians in the battle area, was reasonably expected to be much worse as the Japanese fought to defend the very heart of their empire. The predicted casualties for such an invasion were almost unimaginable. President Franklin D. Roosevelt, who had served as Commander-in-Chief since the beginning of the war, suffered a cerebral hemorrhage and died on 12 April and was replaced by Harry S. Truman. President Truman, after considering the loss of life from battles such as Iwo Jima and Okinawa, looked for less bloody ways to end the war. The alternative came in the form of a top-secret new technology still unknown to the rest of the world; the atomic bomb.