Okinawa Falls to U.S. Marines
Marines cleared northern Okinawa, XXIV Corps wheeled south across the narrow waist of Okinawa.
The 7th and 96th Infantry Divisions encountered fierce resistance from Japanese troops holding fortified positions on high ground and engaged in desperate hand to hand combat in west-central Okinawa along Cactus Ridge, about five miles (8 km) northwest of Shuri. By the night of April 8 the XXIV Corps had cleared these and several other strongly fortified positions. They suffered over 1,500 battle casualties in the process, while killing or capturing about 4,500 Japanese, yet the battle had only just begun, for it was now realized they were merely outposts guarding the Shuri Line.
The next American objective was Kakazu Ridge, two hills with a connecting saddle that formed part of Shuri's outer defenses. The Japanese had prepared their positions well and fought tenaciously. Fighting was fierce. Japanese soldiers hid in fortified caves armed with hidden machine guns and explosives; American forces often lost many men before clearing the Japanese out from each cave or other hiding place. The Japanese would send the Okinawans at gunpoint out to acquire water and supplies for them, which induced casualties among civilians. The American advance was inexorable but resulted in massive casualties sustained by both sides.
As the American assault against Kakazu Ridge stalled, General Ushijima, influenced by General Chō, decided to take the offensive. On the evening of April 12, 32nd Army attacked American positions across the entire front. The Japanese attack was heavy, sustained, and well organized. After fierce close combat the attackers retreated, only to repeat their offensive the following night. A final assault on April 14 was again repulsed. The entire effort led 32nd Army's staff to conclude that the Americans were vulnerable to night infiltration, but that their superior firepower made any offensive Japanese troop concentrations extremely dangerous, and they reverted to their defensive strategy.
The 27th Infantry Division, which had landed on April 9, took over on the right, along the west coast of Okinawa. General Hodge now had three divisions in the line, with the 96th in the middle, and the 7th on the east, with each division holding a front of only about 1.5 miles (2.4 km).
Hodge launched a new offensive of April 19 with a barrage of 324 guns, the largest ever in the Pacific Ocean Theater. Battleships, cruisers, and destroyers joined the bombardment, which was followed by 650 Navy and Marine planes attacking the enemy positions with napalm, rockets, bombs, and machine guns. The Japanese defenses were sited on reverse slopes, where the defenders waited out the artillery barrage and aerial attack in relative safety, emerging from the caves to rain mortar rounds and grenades upon the Americans advancing up the forward slope.
A tank assault on Kakazu Ridge, launched without sufficient infantry support in the hope of a breakthrough, failed with the loss of 22 tanks. Although flame tanks cleared many cave defenses, there was no breakthrough, and the XXIV Corps lost 720 killed, wounded or missing. The losses might have been greater, except for the fact that the Japanese had practically all of their infantry reserves tied up farther south, held there by another feint off the Minatoga beaches by the 2nd Marine Division that coincided with the attack.
At the end of April, the 1st Marine Division relieved the 27th Infantry Division, and the 77th Infantry Division relieved the 7th. When the 6th Marine Division arrived, III Amphibious Corps took over the right flank and Tenth Army assumed control of the battle.
On May 4, the 32nd Army launched another counteroffensive. This time Ushijima attempted to make amphibious assaults on the coasts behind American lines. To support his offensive, the Japanese artillery moved into the open. By doing so they were able to fire 13,000 rounds in support but American counter-battery fire destroyed 19 guns on May 4 and 40 more over the next two days. The attack was a complete failure.
Buckner launched another American attack on May 11. Ten days of fierce fighting followed. On May 13, troops of the 96th Infantry Division and 763d Tank Battalion captured Conical Hill. Rising 476 feet (145 m) above the Yonabaru coastal plain, this feature was the eastern anchor of the main Japanese defenses and was defended by about 1,000 Japanese. Meanwhile, on the opposite coast, the 6th Marine Division fought for "Sugar Loaf Hill". The capture of these two key positions exposed the Japanese around Shuri on both sides. Buckner hoped to envelop Shuri and trap the main Japanese defending force.
By the end of May, monsoon rains which turned contested slopes and roads into a morass exacerbated both the tactical and medical situations. The ground advance began to resemble a World War I battlefield as troops became mired in mud and flooded roads greatly inhibited evacuation of wounded to the rear. Troops lived on a field sodden by rain, part garbage dump and part graveyard. Unburied Japanese bodies decayed, sank in the mud, and became part of a noxious stew. Anyone sliding down the greasy slopes could easily find their pockets full of maggots at the end of the journey.
On May 29, Major General Pedro del Valle, commanding the 1st Marine Division, ordered Company A, 1st Battalion, 5th Marines to capture Shuri Castle. Seizure of the castle represented both strategic and psychological blows for the Japanese and was a milestone in the campaign. Del Valle was awarded a Distinguished Service Medal for his leadership in the fight and the subsequent occupation and reorganization of Okinawa. Shuri Castle had been shelled for 3 days prior to this advance by the USS Mississippi. Due to this, the 32nd Army withdrew to the south and thus the marines had an easy task of securing Shuri Castle. The castle, however, was outside the 1st Marine Division's assigned zone and only frantic efforts by the commander and staff of the 77th Infantry Division prevented an American air strike and artillery bombardment which would have resulted in many casualties due to friendly fire.
Either by design or the "fog of war", Buckner did not detect the Japanese general retreat to their second line of defense in the Kiyan Peninsula, which ultimately led to the greatest slaughter on Okinawa in the latter stages of the battle, including the deaths of thousands of civilians.
By June 4, only some 30,000 poorly-armed (most of their heavy and even personal weapons lost during the withdrawal) soldiers were left in the 32nd Army, including few (20%) surviving trained combat troops. In addition, there were 9,000 IJN troops supported by 1,100 militia holed up at the fortified area of the Okinawa Naval Base Force in the Oroku Peninsula.
Later that day, the Americans launched an amphibious assault on the Oroku Peninsula in order to secure their western flank. After several days of bitter fighting, the Japanese were pushed to the far south of the island.
On June 18, Buckner was killed by enemy artillery fire while monitoring the progress of his troops. Buckner was replaced by Roy Geiger. Upon assuming command, Geiger became the only U.S. Marine to command a numbered army of the U.S. Army in combat. He was relieved five days later by Joseph Stilwell.
The island fell on June 21, 1945, although some Japanese continued fighting, including the future governor of Okinawa Prefecture, Masahide Ota.
Ushijima and Chō committed suicide by seppuku in their command headquarters on Hill 89 in the closing hours of the battle. Colonel Yahara had asked Ushijima for permission to commit suicide, but the general refused his request, saying:
"If you die there will be no one left who knows the truth about the battle of Okinawa. Bear the temporary shame but endure it. This is an order from your army Commander."
Yahara was the most senior officer to have survived the battle on the island, and he later authored a book entitled The Battle for Okinawa.
The battle proceeded in four phases: first, the advance to the eastern coast (April 1-4); second, the clearing of the northern part of the island (April 5-18); third, the occupation of the outlying islands (April 10 - June 26); and fourth, the main battle against the dug in elements of the 32nd Army which began on 06 April and did not end until 21 June. Although the first three phases encountered only mild opposition, the final phase proved extremely difficult because the Japanese were well entrenched in and naval gunfire support was ineffective.