Prior to the invasion of Okinawa itself, Admiral Turner ordered an American strike force to seize a group of islands, the Keramas, off Okinawa’s southwest coast, as well as a small adjacent group called the Keise Shimas. The Keramas contained a substantial anchorage, which would prove to be an ideal facility for ships, either those waiting to unload off the Okinawan beaches or those that were damaged by the kamikaze attacks during the landings. A bonus for the Americans was the discovery of a large flotilla of suicide motor boats that the Japanese planned to use against the U.S. fleet.
D-day was set for April 1, 1945, and a colossal shelling of the Hagushi beach preceded the movement ashore by the Army and Marine assault troops. Carrier planes swooped down to strafe the beaches where the Americans were to land. The tremendous barrage and air attack accomplished virtually nothing as far as the Japanese were concerned, for General Ushijima had the majority of his troops safely hidden away in the caves and tunnels of the Naha-Shuri-Yonabaru Line.
The Marines of the III Amphibious Corps moved north after landing; the Army’s XXIV Corps headed south. Initially, neither the Army nor the Marine contingents encountered any meaningful opposition. Some Okinawan Home Guard draftees had been stationed at the island’s midpoint, but they quickly gave way and retreated when confronted by the Americans. The 1st Marine Division quickly crossed the island’s narrow Ishikawa isthmus, cutting off any direct communication between the Japanese defenders north and south of the incursion.
The 6th Marine Division, under Maj. Gen. Lemuel C. Shepherd, headed north, moving to the mouth of the Motobu Peninsula without encountering any meaningful resistance. There, they faced formidable resistance from Colonel Takehiko Udo and his 3,000-man 2nd Infantry Unit of the reconstituted 44th Brigade, well dug in on Mount Yae Taki. It took the 6th, aided by heavy bombardment from naval vessels offshore as well as supporting air strikes, almost three weeks to secure the island’s northernmost reaches, leaving only the heavily entrenched Japanese forces in the island’s south to combat.
Meanwhile, Japanese Admiral Matome Ugaki had launched his air attacks against the American shipping anchored at Hagushi Bay. These attacks were an essential part of the Japanese strategy to defeat the invading American forces. Ugaki had over 3,000 planes, both conventional and kamikaze, under his command. At the close of Easter week, some 700 planes took off from Kyushu and Taiwan to raid Hagushi.
Known as Operation Ten-Go, Ugaki’s plan was to disrupt American shipping and prevent it from providing the necessary fire support, arms, and equipment to the Tenth Army ashore. Ugaki called the scheduled aerial strikes kikusui or “Floating Chrysanthemums.”
The American ships and aircraft fought the Japanese pilots with every means at their disposal, but defense proved difficult when an enemy flyer was prepared to commit suicide by diving his aircraft into his target. In their initial mass attack, the Japanese sank eight ships and damaged another 10.
Throughout the battle for Okinawa, the Japanese, employing their kikusui tactics, conducted some 10 massed kamikaze attacks and nearly 900 separate air raids against American forces. Japanese air strength was totally destroyed in the attacks, including approximately 1,900 kamikazes. In total, the Japanese sank 36 American ships and damaged an additional 368.
The loss of two particular ammunition ships to the kamikazes did temporarily impede the movement of Buckner’s forces in their attempt to dislodge the enemy ashore. The Hobbs Victory and the Logan Victory, sunk during these raids, carried the phosphorus incendiary shells and 81mm mortar rounds needed to flush the Japanese defenders from their defensive cave positions.
In response to the Japanese air attacks, Admiral Spruance ordered Vice Admiral Marc C. Mitscher and his Task Force 58 carrier air group to strike Japanese airfields on Kyushu. These attacks were designed to reduce the pressure of the kamikaze attacks on American shipping. Admiral Nimitz, from his Honolulu headquarters, also prevailed on the U.S. Army Air Forces to employ heavy B-29 bombers to carry out the same mission. The damage caused to the aircraft parked on Japanese airfields reduced to some degree the kamikaze threat to the American fleet stationed off Okinawa.
In Successive Waves the American Aircraft Torpedoed, Bombed, and Strafed the Yamato and Its Accompanying Cruiser and Destroyers.
In a vain effort to support the Japanese defenders, the Imperial Navy dispatched the cream of its remaining fleet, headed by the super battleship Yamato, to aid in the island’s defense. On April 6, the Yamato, accompanied by the cruiser Yahagi and eight destroyers, steamed out of Tokyo Bay, bound for Okinawa.
The Japanese flotilla lacked air cover. American submarines cruising off the Japanese coast quickly spotted the task force and reported its position to Admiral Mitscher. The following morning the American admiral sent a huge force of aircraft to attack the Yamato and its consorts. In successive waves the American aircraft torpedoed, bombed, and strafed the battleship and its accompanying cruiser and destroyers. In a few hours, the Yamato, the Yahagi, and four of the eight destroyers were sunk. So ended any real attempt by the Japanese Navy’s surface vessels to aid in Okinawa’s defense.
The drive to Okinawa’s south, spearheaded by the XXIV Corps’ 7th and 96th Divisions, quickly encountered strong resistance, for it was here that the bulk of General Ushijima’s 32nd Army troops awaited the American attack. On April 4, the 7th and 96th reached the Naha-Shuri-Yonabaru Line. In a three-day attack lasting from April 9-12, they attempted a direct frontal assault against a key Japanese strongpoint, the Kakazu Ridge. The Americans lost 22 of the 30 tanks committed to the attack. Failure to provide infantry support for the vehicles permitted Japanese suicide squads to move in and disable the tanks with satchel charges.
The Americans were repulsed in this attempt by determined resistance, operating from well- protected firing positions. It soon became apparent that direct frontal assaults against the Japanese defense line would prove to be expensive in terms of men, supplies, and equipment.
The Imperial Japanese Army’s defenses consisted of more than a line, of course. The defenders had utilized every hill, escarpment, and ravine in front of Shuri Castle for some 31/2 miles to forestall the American advance. General Ushijima had his men dig far down into the earth, fashioning a series of tunnels, caves, and foxholes impervious to shelling by the heavy weaponry of the American naval forces lying off the island’s coast. The 32nd Army had a formidable supply of weapons of its own—heavy artillery, mortars, and machine guns—to reinforce its defensive positions. It used huge 320mm mortars against the advancing Americans with deadly effectiveness.
Moreover, the rugged terrain precluded the successful use of American armor in many locales. Japanese maps captured during the battle convinced the American commanders that the Shuri defenses were the strongest yet encountered in the Pacific. Another tactic that proved productive for the Japanese was the stationing of their defensive positions on the reverse slopes of the hills they defended. From these positions they could lob heavy mortar shells on the Americans advancing up the face of the hill as well as targeting their enemy as they came over the crests.
General Cho, greatly heartened by the accomplishments of the 32nd Army in repulsing the Americans during their initial drive against the Shuri Line, prevailed on his commander, General Ushijima, to launch a counterattack. Colonel Yahara, Ushijima’s senior staff officer and a proponent of defensive warfare, argued against such a move, but General Cho succeeded in winning his point with Ushijima.
On April 12, the Japanese 24th Division, together with the 44th Independent Mixed Brigade and the 272nd Independent Infantry Battalion of the 62nd Division, attacked the American positions facing the Naha-Shuri-Yonabaru Line. The Japanese failed to break through and lost over 1,500 men in the effort. The destruction of these front-line troops ultimately reduced the ability of the Japanese to maintain their existing defensive positions.
Cho’s ill-conceived plan conflicted with the original Japanese strategy to assume a fixed defensive position and thus maximize the losses to American forces trying to break through. As Colonel Yahara foresaw, when holed up in caves on the reverse slopes of ridges and escarpments the Japanese defenses cost the Americans dearly. But outside the caves, on the attack, the Japanese lost their tactical advantage and suffered extensive losses when exposed to the American heavy artillery, mortar, and naval gunfire.
On April 18, General John R. Hodge’s 7th and 96th Divisions, now strengthened by the addition of the 27th on their right, or western, flank, renewed their attack on the Japanese fixed defenses. Again, the forward progress of Hodge’s troops was stopped with little gain, the Americans sustaining 750 casualties in this second unsuccessful attempt.
The 27th sustained more losses than any other American division during that frontal assault. Moreover, it had not been at full strength when it had arrived on Okinawa. Buckner also had at his disposal the III Marine Amphibious Corps, now that the Marines had completed their other assignments in the island’s north. Buckner’s failure to employ these experienced Marine divisions instead of depending on the less well trained and shorthanded 27th can only be ascribed, according to Marine historian Robert Leckie, to the general’s desire to have Army troops credited with defeating the Japanese. Nevertheless, the Americans persisted in their frontal attacks against Japanese fixed emplacements. For the next five days, in hand-to-hand fighting, they attacked the Japanese entrenchments and stormed and captured the Kakazu Ridge. Finally, on the night of April 23, with the northernmost positions of his Naha-Shuri-Yonabaru Line breached in a number of key areas, General Ushijima retreated to his next line of defense.