Hell’s Own Cesspool: Why Okinawa Was World War II's Most Brutal Battle

Wikimedia Commons
March 29, 2019 Topic: Security Region: Asia Blog Brand: The Buzz Tags: MilitaryTechnologyWeaponsWarHistory

Hell’s Own Cesspool: Why Okinawa Was World War II's Most Brutal Battle

Welcome to hell on Earth.

On Easter morning, April 1, 1945, the Pacific island of Okinawa trembled beneath an earthshaking bombardment from American combat aircraft overhead and ships steaming offshore in preparation for an amphibious landing of unprecedented magnitude. The commander of Japan’s massive 32nd Imperial Army, Lt. Gen. Mitsuru Ushijima, stood quietly on the crest of Mount Shuri near the southern end of the island, calmly watching the spectacle. He and his chief of staff, Maj. Gen. Isamu Cho, and his senior operations officer, Colonel Hiromichi Yahara, watched through binoculars as the American landing force—four infantry divisions commanded by U.S. Army Lt. Gen. Simon Bolivar Buckner—disembarked from some 1,000-odd landing craft and pushed ashore unchallenged.

For almost a year Ushijima’s army, more than 100,000 strong, had been busy constructing an intricate system of hidden bunkers and fortified ridges in Okinawa’s hilly southern region. Thousands of island residents had been impressed to help build the Japanese defenses. Ushijima had stationed the bulk of his strength in the south and planned to lure the American invasion forces into a catastrophic battle of attrition after allowing them to land on the island unmolested. The Japanese strategy was to drive off the American fleet with conventional attacks and suicidal kamikaze attacks and then annihilate the stranded invasion force. So many American soldiers, sailors, and Marines would perish, Ushijima reasoned, that the Americans would shrink back with horror at the mere thought of invading the Japanese mainland, some 350 nautical miles away.

As American tank and infantry units moved toward the southern end of the island, they would confront an intricate system of two concentric defensive lines constructed along a series of hills, ridges, and draws—the Machinato Line—and behind it the even more heavily fortified Shuri Line. The defenses were manned by veteran, well-armed Japanese soldiers who would remain loyal to their Bushido code of warfare and fight to the death rather than be captured. Yahara, a gifted strategist who helped design and implement the Japanese strategy, was short on tanks but had stockpiled hundreds of heavy weapons and artillery pieces of every caliber—150mm howitzers, 120mm mortars, 47mm antitank guns, and the dreaded 320mm “spigot” mortars—in hidden caves and concrete bunkers that were virtually impervious to air and artillery fire. Yahara’s concept of a yard-by-yard war of attrition, or jikyusen, was a radical departure from previous Japanese island defenses, all unsuccessful, which had concentrated on annihilating the enemy at the water’s edge with massive banzai charges and frontal assaults.

Okinawa: A Strategic Island

The American military wanted Okinawa for three reasons: its seizure would sever the remaining southwest supply line to resource-starved Japan; American medium-range bombers could reach the Japanese mainland from the four airfields on the island; and Okinawa’s harbors, anchorages, and airfields could serve as a final staging area for the planned late-1945 invasion of the Japanese mainland itself. A huge assemblage of forces from Admiral Chester Nimitz’s Central Pacific island-hopping campaign and General Douglas MacArthur’s Southwest Pacific advance converged on Okinawa. In all, Buckner commanded more than 180,000 troops from four Army divisions (the 7th, 27th, 77th, and 96th) under Maj. Gen. John Hodge, and three Marine divisions (the 1st, 2nd, and 6th) under Maj. Gen. Roy Geiger. It was many more troops than Buckner’s namesake father had commanded—and surrendered to Ulysses S. Grant—at Fort Donelson, Tennessee, during the American Civil War.

The Japanese invasion of China in the 1930s initially had little impact on the inhabitants of the Ryukyu Island chain, which runs southwest from the Japanese home island of Kyushu toward Taiwan. Despite its size—it was the largest of the Ryukyu Islands—and its dense native population, Okinawa had neither surplus food nor significant industry to assist the Japanese war effort. The island’s main wartime contribution was the production of sugar cane, which was converted into commercial alcohol for torpedoes and engines. From the first days of the Pacific War, Okinawa was fortified as the front line of defense for mainland Japan. Land and farms were forcibly expropriated throughout the island, and Japan’s Imperial Army began the construction of numerous air bases. Almost half a million Okinawans were intermingled with the Japanese garrison as active, if unwilling, participants in the island’s defense. To keep them loyal, Ushijima had propagandized the populace by telling them that capture by American forces would result in torture, rape, and death, to which suicide was infinitely preferable.

By autumn 1944, Okinawa had been targeted for invasion by Allied forces. The largest amphibious assault of the Pacific War, dubbed Operation Iceberg, would involve assembling one of the greatest naval armadas in history. Admiral Raymond Spruance’s Fifth Fleet included more than 40 aircraft carriers, 18 battleships, 200 destroyers, and hundreds of assorted support ships. The initial assault on the 60-mile-long island was planned for April 1, 1945. On September 29, 1944, B-29 bombers conducted the initial reconnaissance mission over Okinawa and its outlying islands. On October 10, the day after the fearsome and fanatical General Cho boasted to a group of Okinawans in the capital city of Naha that the Japanese defenders would win a decisive victory, nearly 200 of Admiral William “Bull” Halsey’s planes struck Naha in five separate waves and almost devastated the city. Meanwhile, the U.S. Air Force, under the leadership of General Curtis LeMay and operating from bases in the Mariana Islands, began a strategic bombing campaign using B-29s against the mainland of Japan, a campaign that culminated in horrific incendiary raids in March 1945.

Less heralded, but arguably more effective in undermining Tokyo’s military strategy, was the extraordinary success of the American submarine fleet. In 1944 alone, approximately a half million tons of Japanese shipping was sunk by American subs. By early 1945 it was too hazardous for Japanese troop ships to attempt to travel outside the main islands.

The Defender’s Advantage

In mid-March 1945, a combined British-American fleet of more than 1,300 ships gathered off Okinawa to prepare for the naval bombardment; the first kamikaze attacks of the campaign began on March 18. Named for the “divine wind”—typhoons that in 1274 and 1281 had blown away Kublai Khan’s Mongol armadas and saved Japan from invasion—the Kamikaze Special Attack Corps was an example of the desperation infecting Japan’s Imperial Headquarters in Tokyo by early 1944. From the moment Japan entered World War II, it began losing pilots far more rapidly than they could be replaced. By 1944, new Japanese pilots, who were being sent into combat with less than one-third the flight training time that American pilots received, were being shot down in disproportionate numbers. The antiaircraft capabilities of U.S. Navy ships had also increased to such an extent that attacking an American vessel had essentially become a suicide mission anyway. The Japanese decided that it would be more practical for their pilots to deliberately plunge their aircraft into the enemy’s warships, ensuring the ship’s destruction as well as their pilots’. The operational creed became “one plane, one ship.” Some 4,000 Japanese planes were stockpiled for the kamikaze attacks.

American troops secured two positions prior to landing day. The small island groups of Kerama and Keise, southwest of Okinawa, could be used to provide anchorages for ships and as an artillery base to back up ground forces once they went ashore. Against occasionally stiff resistance from isolated garrisons, American forces secured Kerama on March 28 and Keise on March 31. At Kerama, they also destroyed 350 suicide boats, speedy craft loaded with depth charges that the Japanese had planned to use against the Allied fleet. U.S. planners anticipated a bloodbath when the main landing took place since it would be the first time that American and Japanese forces would clash on Japanese soil. American intelligence, unfortunately, grossly underestimated the size of the garrison on Okinawa, placing the number at no more than 65,000 troops. In fact, Okinawa harbored some 110,000 crack Japanese soldiers, at least five times the number that had badly bloodied U.S. forces at Iwo Jima. In addition, some 20,000 Okinawans had been drafted into home defense units, or boeitai, to serve as auxiliary forces.

The American planners, who saw the Okinawa campaign as an exercise in overwhelming material and numerical advantages, were unaware that many advantages remained with the Japanese defenders. In the war of attrition to come, the Japanese had packed more than 100,000 troops into the southern third of the island where they, not the Americans, possessed the high ground and the greater concentration of force. The island itself was larger than many of the other Pacific atolls stormed in earlier campaigns, and its unpredictable weather, razor-sharp coral rocks, and dense vegetation gave defenders even more advantages than they had enjoyed at Iwo Jima, where a garrison of 23,000 Japanese troops had claimed the lives of 6,000 Marines.

The Machinato Line

The people of Okinawa had long been resigned to the severe typhoons that periodically swept their island, but nothing in their experience equaled the tetsu no bow—storm of steel—that pounded the island on April 1 preceding the American landing. Indeed, it was the heaviest concentration of naval gunfire ever to support an amphibious landing. While the 2nd Marine Division conducted a demonstration landing on Okinawa’s southeast beaches, the 7th and 96th Infantry Divisions of the Army’s XXIV Corps and the 1st and 6th Marine Divisions of the III Marine Amphibious Corps crossed the Hagushi beaches. Some 16,000 troops landed in the first hour, and by nightfall more than 60,000 American troops were safely ashore, with another 120,000 waiting in ships offshore. Marine and Army units advanced rapidly inland toward the vital airfields of Kadena and Yontan. Within three hours, troops of the 6th Marine Division had seized Yontan, while soldiers of the 7th Infantry Division advanced to secure Kadena and continued inland. By day’s end, the Americans had secured a beachhead nine miles wide and three miles deep, at a remarkably small cost of 28 men killed or missing and 104 wounded.