World War II Pacific: Battles and Campaigns from Guadalcanal to Okinawa 1942-1945 (WW2 Pacific Military History Series)

by Daniel Wrinn

  Operation Iceberg

  The battle of Okinawa covered a seven-hundred-mile arc from Kyushu to Formosa. It involved a million combatants—Japanese, Americans, British, and Okinawan natives. This battle rivaled the Normandy invasion because it was the biggest and bloodiest operation of the Pacific War. In eighty-two days of combat, Allied forces and unfortunate noncombatants suffered an average of 3,000 lives lost a day.

  By the spring of 1945, the Empire of Japan was a wounded wild animal: desperate, cornered, and furious. Japanese leaders knew Okinawa under Allied control would be transformed into “the England of the Pacific.” It would serve as a staging point for the invasion of the sacred homeland. The Japanese would sacrifice everything to avoid the unspeakable disgrace of unconditional surrender and foreign occupation.

  The US Navy was presented with its greatest operational challenge to date: how to protect a gigantic and exposed amphibious task force tethered to the beachhead against Japanese kamikaze attacks. Okinawa would be the ultimate test of US amphibious power and projection. Could Allied forces in the Pacific Theater plan and execute such a massive assault against a heavily defended landmass? Could the Allies integrate the tactical capabilities of all the services and fend off every imaginable form of counterattack while maintaining operational momentum?

  Operation Iceberg was not executed in a vacuum. Preparatory action to the invasion kicked off at the same time campaigns on Iwo Jima and the Philippines were still being wrapped up—another strain on Allied resources. But as dramatic and sprawling as the battle of Okinawa proved to be, both sides saw this contest as an example of the even more desperate fighting soon to come with the invasion of the Japanese home islands. The closeness of Okinawa to Japan was well within medium bomber and fighter escort range. Its valuable military ports, anchorages, airfields, and training areas made this skinny island imperative for Allied forces—eclipsing their earlier plans for the seizure of Formosa.

  Okinawa is the largest of the Ryukyuan Islands. The island sits at the apex of a triangle nearly equidistant to strategic areas. Formosa is 330 miles to the southwest, Kyushu is 350 miles to the north, while Shanghai is 450 miles to the west. As on so many Pacific battlefields, Okinawa had a peaceful heritage. Officially an administrative prefecture of Japan (forcibly seized in 1879), Okinawans were proud of their long Chinese legacy and unique sense of community.

  Imperial headquarters in Tokyo did little to garrison or fortify Okinawa at the beginning of the Pacific War. After the Allies conquered Saipan, Japanese headquarters sent reinforcements and fortification materials to critical areas within the “Inner Strategic Zone,” Peleliu, the Philippines, Iwo Jima, and Okinawa.

  Imperial Japanese headquarters on Okinawa formed a new field army: the Thirty-second Army. They funneled different trained components from Japan’s armed perimeter in China, Manchuria, and the home islands. American submarines took a deadly toll on these Japanese troop movements. On June 29, 1944, the USS Sturgeon torpedoed the transport Toyama Maru. She sank with a loss of 5,600 troops of the 44th Independent Mixed Brigade en route for Okinawa. It would take the Japanese the rest of the year to replace that loss.

  In October 1944, US Joint Chiefs decided to act on the strategic value of the Ryukyus. They tasked Admiral Nimitz with seizing Okinawa after the Iwo Jima campaign. The Joint Chiefs ordered Nimitz to seize, occupy, and defend Okinawa before transforming the captured island into an advanced staging base for the invasion of Japan.

  Nimitz turned to his most veteran commanders to execute this mission. Admiral Spruance, the victor of Midway and the Battle of the Philippine Sea, would command the US Fifth Fleet (debatably the most powerful armada of warships ever assembled). Admiral Kelly Turner, veteran of the Solomons and Central Pacific landings, would command all amphibious forces under Spruance. But Kelly Turner’s military counterpart would no longer be the old warhorse General Holland Smith. Iwo Jima was Smith’s last fight. Now the expeditionary forces had grown to the size of a field army with 182,000 assault troops. Army General Simon Buckner (son of the Confederate general who fought against Grant at Fort Donaldson in the American Civil War) would command the newly formed US Tenth Army.

  General Buckner made sure the Tenth Army reflected his multi-service composition. Thirty-four Marine officers served on Buckner’s staff, including General Oliver P. Smith as his deputy Chief of Staff. Smith later wrote: “the Tenth Army became, in effect, a joint task force.”

  Six veteran divisions, two Marine and four Army, composed Buckner’s landing force. A division from each service was marked for reserve duty—another sign of the growth of Allied amphibious power in the Pacific. Earlier in the war, Americans had landed one infantry division on Guadalcanal, two in the Palaus, and three each on Iwo Jima and Saipan. But by spring 1945, Buckner and Spruance could count on eight experienced divisions besides those still on Luzon and Iwo Jima.

  The Tenth Army had three major operational components. Army General John Hodge commanded the XXIV Corps, composed of the 77th and 96th Infantry Divisions (with the 27th Infantry Division in floating reserve and the 81st Infantry Division in area reserve). Marine General Roy Geiger commanded the III Amphibious Corps, composed of the 1st and 6th Marine Divisions (with the 2nd Marine Division held in floating reserve). Marine General Francis Mulcahy commanded the Tenth Army’s Tactical Air Force and the 2nd Marine Aircraft Wing.

  The Marine components for Operation Iceberg were scattered. The 1st Marines had returned from Peleliu to “Pitiful Pavuvu” in the Russell Islands to prepare for the next fight. The 1st Marine Division had been the first to deploy into the Pacific. They executed brutal amphibious campaigns on Guadalcanal, Cape Gloucester, and Peleliu. Over one-third of the 1st Marines were veterans of two of those battles.

  Pavuvu’s tiny island limited work-up training, but a large-scale exercise on neighboring Guadalcanal enabled the division to integrate its replacements and returning veterans. General del Valle drilled his Marines in tank-infantry training under the protective umbrella of supporting howitzer fire.

  The 6th Marine Division was the only division formed overseas in the war. General Lemuel Shepherd activated the colors and assumed command on September 12, 1944. While this unit was newly formed, it was not green—several former Marine Raiders with combat experience comprised the heart of this Marine division. General Shepherd used his time and the more extensive facilities on Guadalcanal to conduct work-up training from the platoon to the regimental level. He looked ahead to Okinawa and emphasized rapid troop deployments and large-scale operations in built-up combat areas.

  General LeRoy Hunt commanded the 2nd Marine Division. Hunt’s Marines had returned to Saipan after the conquest of Tinian. The division had absorbed 8,000 replacements and trained for a wide-ranging series of mission assignments as a strategic reserve. The 2nd Division possessed a vital lineage in the Pacific War at Guadalcanal, Tarawa, Saipan, and Tinian. Its presence in the Ryukyus’ waters would establish a fearsome “amphibious force-in-being” to distract the Japanese on Okinawa. This division would pay an unequal price for its bridesmaid role in the coming campaign.

  The Marine assault force preparing for Okinawa was dealt another organizational change—the fourth of the war. Marine headquarters constantly reviewed “lessons learned” in the war and had just completed a series of revisions to the table of organization for its divisions and components. While it would not become official until a month after the landing, the divisions had already made most changes.

  The overall size of each division increased to 19,176 (from 17,465). This was done by adding an assault signal company, a rocket platoon (Buck Rogers Men), a fifty-five man assault platoon in each regimental headquarters, and a war dog platoon. Motor transport, artillery, and service units also received slight increases, as did machine-gun platoons in each rifle company. But the most timely weapons change happened by replacing the 75mm half-tracks with the new M-7s (105mm self-propelled howitzer). Artillery regiment purists did not approve of th
ese weapons being deployed by the infantry. These M-7s would not be used as massed howitzers but as direct fire “siege guns” against the thousands of fortified caves on Okinawa.

  Marine Corps Headquarters backed up these last-minute changes by providing the required replacements to land the assault divisions at full strength. Sometimes the skills required did not match. Some artillery regiments absorbed a flood of radar technicians and anti-aircraft artillery gunners from old defense battalions. But the manpower and equipment shortfalls that had plagued earlier operations were overcome by the time the assault force embarked on Operation Iceberg.

  Even this late in the war, operational intelligence was unsatisfactory before the landing. At Tarawa and Tinian, the pre-assault combat intelligence had been brilliant. But at Okinawa, the landing force did not have accurate figures of the enemy’s weapons or abilities.

  The cloud cover over the island prevented accurate and complete photo-reconnaissance. Also, the ingenuity of the Japanese commander and the extraordinary digging skills of the enemy garrison helped disguise the island’s true defenses.

  Japanese Defenses

  Okinawa is sixty miles long, but only the lower third of the island had the military objectives of anchorages, ports, and airfields. In August 1944. Japanese General Mitsuru Ushijima took command of the Thirty-second Army. He understood the fight would be fought in the south and concentrated his forces there.

  He decided to not challenge the probable Allied landings in Hagushi along the broad beaches of the southwest coast. He believed that doing so would lose him the Kadena and Yontan Airfields. This decision allowed him to conserve his forces and fight the only battle that stood a chance: an in-depth defense, underground and protected from the overpowering Allied air and arms superiority.

  This clash of cave warfare and attrition would be like the recent battles on Peleliu and Iwo Jima. Each had taken a terrifying cost to Allied invaders. General Ushijima sought to replicate this strategy. He would go underground and sting the Allies with high caliber gunfire from his freshly excavated fire-port caves. He believed by bleeding the landing force and bogging down their momentum, he could buy the Imperial Army and Navy’s air arms enough time to destroy the fifth fleet with massed kamikaze attacks.

  General Ushijima had 100,000 Imperial troops on the island, including thousands of Okinawan Home Guard (conscripts known as Boeitai). He had a disproportionate number of heavy weapons and artillery in his command. The Allies in the Pacific would not encounter a more formidable concentration of 47mm antitank guns, 320mm spigot mortars, 120mm mortars, and 150mm howitzers. The strategic decision to invade Peleliu, Iwo Jima, and the Philippines before Okinawa gave the enemy seven months to develop their defenses.

  Allied forces had already seen what the Japanese could do to fortify a position in a short time. On Okinawa they achieved stunning success. They worked almost exclusively with hand tools: not one bulldozer on the entire island. The Japanese dug miles of underground fighting positions and honeycombed southern Okinawa’s ridges and draws. They stocked each position with reserves of food, water, ammunition, and medical supplies. Allied forces anticipated a fierce defense of the southwestern beaches and the airfields, followed by a general counterattack. Then, the battle would be over except for some mop-up and light patrolling.

  The Allies could not have been more mistaken.

  The assault plan called for the advance seizure of the Kerama Retto Islands after several days of preparatory air and naval bombardment. Followed by a massive four-division assault on the Hagushi Beaches. During the primary assault, the 2nd Marine Division, with a separate naval task force, would duplicate the assault on Okinawa’s southeast coast (Minatoga Beaches).

  Love-Day (chosen to avoid planning confusion with D-Day being planned for Iwo Jima) would happen on April 1, 1945. Hardly anyone failed to remark about the irony of April Fool’s Day and Easter Sunday.

  The US Fifth Fleet was a breathtaking sight as it steamed toward the Ryukyus. Marines who’d returned to the Pacific from the original amphibious offensive on Guadalcanal thirty-one months earlier gaped at the quantity of landing craft in the assault ships. The armada stretched to the horizon—a genuinely incredible, mind-boggling vista.

  On March 26, the 77th Infantry Division skillfully secured Kerama Retto. A move that surprised the Japanese and generated enormous operational dividends. Admiral Turner now had a series of sheltered anchorages to repair ships likely to be damaged by kamikaze attacks. Soldiers discovered stockpiled Japanese suicide boats—over 300 powerboats equipped with high explosive rams to sink the thin-skinned troop transports.

  Major James Jones commanded the Force Reconnaissance Battalion. His battalion paved the way before each landing with stealthy scouting missions the night before. Jones’ recon Marines scouted and found the barren sand spits of Keise Shima undefended. After reporting that welcome news, the Army landed a battery of 155mm “Long Toms” on the small inlets, adding to their significant firepower and the naval bombardment of Okinawa’s southwest coast.

  Admiral Turner’s minesweepers cleared approaches to the southwestern beaches. Navy frogmen and Marines detonated hundreds of man-made obstacles. After seven days of preliminary bombardment, Allied ships fired over 25,000 rounds of 5-inch shells. This shelling produced more of a spectacle than a destructive effect. The Allied forces believed General Ushijima’s troops would be arrayed around the beaches and airfields. While that scale and duration of bombardment would’ve saved many lives on Iwo Jima: on Okinawa, this precious ordinance was largely wasted and produced few results.

  Tensions were high in landing force transports. The 60mm mortar section of Company K, 3/5 Marines learned that the casualty rates on Love-Day were estimated to reach 85%. According to Private First Class Eugene Sledge: “this is not conducive to a good night’s sleep.”

  A Japanese soldier observing the massive armada bearing down on Okinawa wrote in his diary: “it’s like a frog meeting a snake and waiting for the snake to eat him.”

  Land the Landing Force

  The Allied invasion got off to a roaring start. The few enemy defenders still in the area at dawn on April 1 immediately agreed with the wisdom of conceding the beaches to the landing force.

  The massive armada gathered from ports all over the Pacific now bore down on Okinawa’s southwest coast: ready to deploy a 182,000-man landing force onto the beach. The ultimate forcible entry—the embodiment of all painfully learned amphibious lessons from the crude beginnings at Guadalcanal and North Africa.

  Admiral Turner made his final review of the weather conditions in the objective area. As at Iwo Jima, the amphibious assault was fortunate to have good weather for the critical initial landing. Skies were clear, winds and surf were moderate. The temperature was 75 degrees.

  At 0406, Turner ordered: “Land the landing force.” That phrase set off a sequential countdown to the first assault waves smashing into the beaches at H-hour. Combat troops crowded the rails of the transports to witness an extraordinary display of Allied naval power. A sustained bombardment by rockets and shells from hundreds of ships. Formations of Allied attack aircraft streaked low over the beaches: strafing and bombing at will. Japanese fire was ineffective and scattered, even against this massive armada assembled offshore.

  The diversionary force carrying the 2nd Marine Division set out to bait the Japanese with a feint landing on the opposite coast. This amphibious force steamed into position and launched amphibian tractors and Higgins boats loaded with combat Marines in seven waves toward Minatoga Beach. The fourth wave commander paid careful attention to the clock and crossed the line of departure at exactly 0830—the time of the actual H-hour assault on the western coast. Then, the Higgins boats and LVTs turned away and returned to the transports: mission accomplished.

  The diversionary landing achieved its purpose. General Ushijima had placed several front-line infantry and artillery units in the Minatoga Beach area for several weeks as a contingency against an expecte
d secondary landing. His officers reported to Imperial headquarters on Love-Day morning: “enemy landing attempt on east coast blocked with heavy enemy losses.”

  This deception came at a high cost. Kamikaze pilots were convinced this was the main assault. They came in waves and struck the small force that morning, damaging the troopships LST 844 and Hinsdale. The 3/2 Marines and the 2nd Amphibian Tractor Battalion suffered fifty casualties. The troopships lost an equal number of sailors. Ironically, the division that was expected to have the most minor damage or casualties in the battle lost more men than any other division in the Tenth Army that day. According to Operation Officer Colonel Sam Taxis: “we’d requested air cover for the feint but were told the threat was ‘incidental.’”

  In the southwest, the main assault force faced little resistance. A massive coral reef provided an offshore barrier to the beaches on Hagushi. But by early evening, the reef no longer presented a threat to the landing force. Unlike on Tarawa, where the reef dominated the tactical progress of the battle. General Buckner had over 1,400 LVTs to transport the assault waves from ship to shore without delay.

  Eight miles of LVTs churned across the line of departure just behind 360 armored LVT-As that blasted away at the beach with their snub-nosed 75mm howitzers as they advanced the final four thousand yards. Behind the LVTs were 750 amphibious trucks with the first of the direct support artillery battalions. The horizon behind the amphibious trucks was filled with lines of landing boats. They paused at the reef to marry with the outbound LVTs. Marines and soldiers had exhaustively rehearsed transfer line operations—there was no pause in the assault momentum.

  The Bisha Gawa river mouth marked the boundary between IIIAC and XXIV Corps along the Hagushi beaches. The tactical plan called for the two divisions to land abreast—the 6th on the left and the 1st on the right. The endless rehearsal of thousands of hours paid off. The initial assault touched down at 0830: the designated H-hour. Marines stormed out of their LVTs, swarming over the sea walls and berms into the great unknown. The Okinawa invasion had begun. Within the first hour, the Tenth Army had over 16,000 combat troops ashore.