by Daniel Wrinn
The Experimental Rocket Unit was formed in June 1943 and first deployed rail-launched barrage rockets during the fighting in the Solomons. There, heavily canopied jungles limited their efficiency. But once mounted on trucks and deployed in the Central Pacific, these rockets were deadly and effective, especially during the battle on Saipan.
Marines reinforced the trucks’ tailgate to serve as a blast shield. They installed hydraulic jacks to raise and lower the launchers. Crude steel rods were welded to the bumper and dashboard to help the driver align the vehicle with the aiming stakes.
A hilly treeless Iwo proved an ideal battleground for the “Buck Rogers Men.” The 1st Provisional Rocket Detachment supported the 4th and 5th Marine Divisions throughout the battle on Iwo Jima. The Buck Rogers Men fired over 30,000 rockets to support the landing force.
The Rocket Detachment landed on Red Beach on D-Day and lost one vehicle in the surf and several others to heavy enemy fire or loose sand. When the first vehicle reached its firing position intact, it launched a salvo of rockets against Japanese fortifications on the slopes of Suribachi. It detonated an enemy ammunition dump. The detachment supported the Marines advance to the summit, often launching single rockets to clear suspected enemy positions along the route.
As the fighting advanced north, the rocket launchers’ short-range deep angle fire and saturation effect kept them in high demand. They were effective in defilade-to-defilade bombardments. But the distinct flashing telltale blast always caught the attention of the Japanese artillery spotters. The rocket trucks rarely remained in one place long enough to fire more than two salvos. A fast displacement was critical to their survival. Marines knew better than to stand around and wave goodbye—it was time to seek deep shelter from the counter-battery fire sure to follow.
Logistical Support
The logistical effort necessary to sustain the assault force on Iwo Jima was complex, enormous, and learned from previous lessons in Pacific amphibious operations. No other element of the emerging art of amphibious warfare had improved so greatly by the winter of 1945.
While Marines had the courage and firepower to tackle a fortress like Iwo Jima, they would have been crippled without the available amphibious logistical support. The procedures, organizations, and concepts took years to develop. But once in place, they enabled the large-scale conquests on Iwo Jima and Okinawa.
On Iwo Jima, the 8th Field Depot was commanded by Colonel Leland Swindler. This depot served as the nucleus of shore party operations. Swindler coordinated the activities of all shore party operations. The logistical support on Iwo was well-conceived and executed. Liaison teams from the 8th Field Depot accompanied the 4th and 5th Divisions ashore. On D +3, field depot units came ashore, took over the unloading, and continued without interruption.
Every imaginable method of delivering combat cargo ashore was used. This involved “hot cargo,” carried in by the assault waves. Hot cargo was preloaded in on assault waves or floating dumps. This experimental use of one-shot preloaded amphibious trailers, Wilson drums, and a general loading and unloading would be known to future generations as the “assault follow-on echelon.”
Aerial delivery was first by parachute and then via transports landing on the captured runways. The Marine/Navy team experimented with the use of armored bulldozers and sleds loaded with hinged matting delivered by assault waves to clear wheeled vehicles stuck in the soft, volcanic sand. Despite fearsome obstacles: heavy surf, dangerous undertows, foul weather, and formidable enemy fire—the system worked. The combat cargo flowed in and kept casualties and salvaged equipment flowing out.
The occasional shortages were often the result of the Marines meeting a more robust defensive garrison than initially expected. Urgent calls for more demolitions, grenades, mortar illumination rounds, and blood plasma were common. Transport squadrons delivered many of these critical items directly from the Mariana Islands fleet bases.
The field medical support on Iwo was a model of detailed planning and flexible application. Marines received immediate medical attention from their corpsmen and surgeons. But the system from hospitals to grave registration was mind boggling to some of the older veterans. Moderately wounded Marines received full hospital treatment and rehabilitation—often returning directly to their units—this preserved some of the swiftly decreasing combat experience levels in the frontline outfits. The more seriously wounded were stabilized, evacuated, and treated in offshore hospital ships or taken by air to Guam.
Marines fired an extraordinary half-million artillery rounds to support the assault units. Many rounds were lost when the 5th Marine Division’s ammo dump blew up. But the flow never stopped. The shore party used LVTs and amphibious trucks for a fast offloading of ammunition ships dangerously exposed to enemy gunners. Marines helped the shore party hustle munitions onshore and into the neediest hands.
Colonel James Hittle of the 3rd Division (the reserve landing force) shook his head at the “crazy quilt” logistics adopted because of Iwo’s geography. Hittle “appropriated” a transport plane and made regular runs to Guam—returning with fresh beef, beer, and mail. Colonel Hittle sent his transport quartermaster out to sea in an LVT full of war souvenirs to trade for bread, eggs, and fresh fruit.
Hittle was amazed at the density of troops funneled onto the small island: “at one point, we had over 60,000 men occupying less than three and a half miles of broken terrain.” He directed Marine engineers to dig a well near the beach for a freshwater distilling plant. Instead of a saltwater source, engineers discovered steaming mineral water heated by Suribachi’s dormant volcano.
Hittle moved the distilling site, and this spot became a hot shower facility—one of the most popular places on the island.
* * *
Building a relationship with my readers is one of the best things about writing. I occasionally send out emails with details on new releases and special offers. If you’d like to join my free readers group and never miss a new release, just tap here and I’ll add you to the list.
Operation Iceberg
1945 Victory on Okinawa
Seizing Shuri Castle
At dawn on May 29, 1945, the 1st Marine Division began their fifth consecutive week of frontal assaults. This was part of the Tenth Army’s relentless offensive against Japanese defenses in southern Okinawa.
Operation Iceberg’s mission to secure Okinawa was now two months old and badly bogged down. The fast-paced opening had been replaced by weeks of exhausting and bloody attrition warfare against the Shuri Castle.
The 1st Division were hemmed in between two other divisions. They had precious little room to maneuver and had advanced less than a thousand yards in eighteen days. An average of fifty-five murderous yards per day. Their sector was one bristling, honeycombed ridgeline after another—Kakazu, Dakeshi, and Wana.
But just beyond was the long shoulder of Shuri Ridge. Nerve center of the Imperial Japanese Thirty-second Army. The outpost of dozens of forward artillery observers, who’d made life miserable for the Allied landing force. On this wet, rainy, and cold morning, things were different. It was quieter. After days of savage and bitter fighting, Allied forces overran Conical Hill to the east and Sugar Loaf to the west. Shuri Castle no longer seemed invincible.
The 1/5 Marines moved out cautiously and expected the usual firestorm of enemy artillery at any moment. But there was none. Marines reached the crest of Shuri Ridge without a fight. Amazed, the company commander looked west along the road toward the ruins of Shuri Castle: a medieval fortress of ancient Ryukyuan kings.
Soldiers in the Tenth Army expected the Japanese to defend Shuri to the death, but the place seemed lightly held. Spiteful small arms fire came from nothing more than a rearguard. Field radios buzzed with this surprising news. Shuri Castle laid in the distance, ready for the taking. Marines asked for permission to seize their long-awaited prize.
General Pedro del Valle, CO of the 1st Marine Division, didn’t hesitate. According to corps division bounda
ries, Shuri Castle belonged to soldiers of the 77th Infantry Division. General del Valle knew his counterpart, Army General Andrew Bruce, would be furious if the Marines snatched their long-sought trophy before his soldiers could arrive. This was a unique opportunity to grab the Tenth Army’s primary objective. General del Valle gave the go-ahead, and with that, the 1/5 Marines raced along the west ridge against light opposition and secured Shuri Castle.
After General del Valle’s staff did some fancy footwork to keep peace with their army neighbors, they learned the 77th had scheduled a massive castle bombardment that morning. Frantic radio calls averted the near-catastrophe just in time. General Bruce was infuriated by the Marines’ unauthorized initiative. Del Valle later wrote: “I don’t think a single Army commander would talk to me after that.”
Through the inter-service aggravation, Allied forces had achieved much this morning. For two months, Shuri Castle had provided the Japanese with a superb field of observed fire—covering southern Okinawa’s entire five-mile neck. But as the 1/5 Marines deployed into a defensive line within the castle’s rubble, they were unaware that a Japanese rearguard still occupied a massive subterranean headquarters underneath them. Marines soon discovered that directly under their muddy boondockers was the underground headquarters of the Japanese Thirty-second Army. This mammoth complex was over 1,200 feet long and 160 feet deep: all dug by pick and shovel.
The enemy had stolen a march on the approaching Tenth Army. Japanese forces retreated south during the rains and occupied the third (final) ring of their prepared underground defenses: a series of fortified escarpments on the Kiyamu Peninsula.
Seizing Shuri Castle was an indisputable milestone in the Okinawa campaign. Still, it was a hollow victory. Like the flag-raising on Iwo Jima’s Suribachi signified the end of the beginning of that prolonged battle. The capture of Shuri Castle did not end the fighting. The savage slugfest on Okinawa continued for another twenty-four days—while the plum rains fell and the horrors and dying on both sides continued.
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-infantr
y 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 these 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.