Iwo Jima: Amphibious Pinnacle

Iwo Jima was the most heavily fortified island the United States assaulted in World War II. The strate­gic benefits of acquiring airfields within fighter range of Tokyo were significant; the risks in attacking that steep, volcanic fortress—well within Japan’s Inner Defense Zone—were enormous. This was not a mission U.S. am­phibious forces could have tackled earlier in the war. Seiz­ing the island would require full command of the air and sea, overwhelming technological superiority, imaginative naval campaign planning, and violent, sustained am­phibious execution.

Iwo Jima was a latecomer as a potential objective for the U.S. Pacific Fleet. Most planners figured that the cam­paigns in the Philippines and Palaus were precursors to a combined operation against Formosa. Some commanders chafed at this investment of so many resources in a time-consuming campaign far from the Japanese homeland. Vice Admiral Raymond A. Spruance, commanding the Fifth Fleet, believed the wiser choice would be to strike north-by-northwest against the Volcano and Ryuku Islands. Seize Iwo Jima, he suggested, then Okinawa, and then prepare to invade Kyushu and Honshu.

Iwo Jima already had captured the attention of certain other planners. Japan’s Imperial General Headquarters ordered an urgent buildup of Iwo’s defenses as soon as Saipan fell in July 1944.

That same month General Henry H. “Hap” Arnold, Chief of Army Air Forces, asked the Joint Planning Staff to examine the feasibility of assaulting Iwo Jima. Both actions stemmed from anticipation of America’s pending B-29 bomber program. Saipan-based B-29s would bring Tokyo into effective bomber range for the first time in the war. Conversely, Iwo-based Japanese aircraft could intercept the B-29s, provide early warning to Tokyo, and counterattack U.S. bases in the Marianas. The strategic necessity of seizing Iwo Jima soon drove out the Formosa plan. On 3 October 1944, the Joint Chiefs of Staff directed Fleet Admiral Chester Nimitz to capture Iwo Jima. Re­duced to its nub, the Fifth Fleet’s mission was twofold: enhance the strategic bombing campaign; facilitate the ul­timate invasion of the Japanese homeland.

Veteran amphibious planners in the Central Pacific rec­ognized this assignment as a new twist on an old mission. For 40 years, the Navy and Marine Corps had trained to conduct landings for the seizure of advanced naval bases. In the Pacific, this mission had evolved into seizing ad­vanced air bases, first as “unsinkable carriers” in the case of Guadalcanal, Tarawa, and Roi, and increasingly—as at Saipan and now Iwo Jima—in support of the strategic bombing campaign against Japan.

Operation Detachment, the campaign to seize Iwo Jima, was by necessity a stepchild wedged between the larger campaigns of Luzon and Okinawa. This relationship dominated the planning for Detachment. Even as late as 1944–45, the United States lacked the resources to con­duct two simultaneous, full-scale amphibious operations in the Pacific. The Joint Chiefs of Staff twice postponed D-day for Iwo Jima, because slow progress in Luzon delayed the turnover of naval gunfire sup­port ships and specialized land­ing craft from Army General Douglas MacArthur’s forces to the Fifth Fleet. Nor was there any slack at the other end of the schedule. Spruance had to com­plete the seizure of Iwo Jima and reposition his amphibious forces to support the Okinawa campaign well before 1 April.

That was the latest date Oki­nawa could be invaded without incurring undue risk from the summer typhoon season.

These time constraints did not bother Spruance. Each of his principal task force com­manders was a veteran of many months of urgent planning and hard campaigning in the Cen­tral Pacific. Vice Admiral Marc Mitscher commanded the Fast Carrier Task Force (TF-58); Vice Admiral Richmond Kelly Turner commanded the Joint Expeditionary Force; Marine Lieutenant General Holland M. Smith commanded the Expeditionary Troops. Other veteran commanders oc­cupied key billets. Rear Admiral Harry W. Hill com­manded the Attack Force; Rear Admiral W. H. P. Blandy, the Amphibious Support Force (the “Advance Force Com­mander” in modern parlance); and Marine Major Gen­eral Harry Schmidt, V Amphibious Corps. Schmidt would command the largest force of Marines ever com­mitted to a single battle—a three-division landing force numbering 70,000 men. Hill’s command would include 125 amphibious ships and an additional 75 seagoing landing craft. Altogether, 495 ships would surround Iwo Jima during the battle—ten times the force that invaded Guadalcanal in 1942.

Aside from aerial photography (and periscope pho­tographs from the submarine Spearfish (SS-190), U.S. in­telligence collection and analysis prior to Iwo Jima was less productive than for most preceding amphibious cam­paigns. Analysts looked at the island’s severe water short­age and concluded that no more than 13,000 troops could be accommodated there, a 40 percent shortfall. Analysts also believed the senior officer on the island was Major Gen­eral Kotono Osuga, one-time commander of the 2nd Inde­pendent Mixed Brigade, assuming incorrectly that Lieu­tenant General Tadamichi Kuribayashi maintained his headquarters on Chichi Jima, 140 miles away. Planners underestimated the proliferation of Japanese major weapons. “The Japs had more heavy guns than we ex­pected,” admitted Turner to a New York Times reporter during the battle. More significant, little evidence has ever surfaced of any substantial use of intertheater “lessons learned” from the earlier cave fighting at Peleliu.

Smith and Schmidt were more concerned with the on­going dispute with the Navy over the extent of prelimi­nary bombardment allotted to Iwo. The Marines, sensing the difficulty of this forthcoming objective, asked for ten days. “Out of the question,” replied Spruance and Turner. “Three days will suffice.” The Navy saw the greater need to orches­trate tactical surprise, coordinate the bombardment with strikes against Honshu by Mitscher’s fast carriers, and guard against possible incursion by the rem­nants of the Combined Fleet. A logistic restraint also served to limit bombardment. The Pa­cific Fleet had not yet mastered the art of underway replenish­ment of ammunition; gunfire support ships would have to re­tire to a distant anchorage to rearm for any prolonged bom­bardment. The arguments be­came rancorous. Blandy’s gunships would deliver four times the shelling Tarawa received and one-and-one-half times the prep fires at Saipan. Yet the Marines argued that prolonged, deliberate fire—with repeated hits on hard tar­gets—was more critical than gross tonnage delivered.

A greater preliminary bombardment, then, would no doubt have saved Marine lives. The heart of Kuribayashi’s defenses in the Motoyama Plateau remained essentially unscathed during the three days before D-Day. On the other hand, most of Kuribayashi’s emplacements in the north were camouflaged so skillfully and his men so deeply entrenched that they probably would have remained im­pervious to any extended shelling. They had already withstood ten weeks of daily pounding by Seventh Air Force medium bombers without substantial damage.

Planners knew in advance that Iwo’s steep beach and loose volcanic sand would complicate the movement of wheeled vehicles from landing craft to the high-water mark. Admiral Hill and his chief Beachmaster, Captain Carl E. “Squeaky” Anderson, worked furiously to de­vise means of improving beach trafficability. Bulldozers would be in high demand along the beach on D-day; Hill and Anderson fabricated armored shields to protect the operators from sniper fire. The two officers also devel­oped sand sleds and Marston matting, an expeditionary airfield surface, modified so it could be played out from a tracked vehicle to lay an improvised road over the soft sand as a beach exit.

Other planners looked beyond the beach, noting the heights on either flank, sensing how Mount Suribachi and the Rock Quarry would afford the enemy deadly fields of fire. Said Major General Clifton B. Cates, commanding the 4th Marine Division—and a veteran of Belleau Wood in World War I and Guadalcanal and Tinian—“I didn’t like the idea of landing in a bight, where you were flanked on both sides.”

Iwo Jima was the fourth assault landing in 13 months for the 4th Marine Division. The 3d Division, scheduled initially in a reserve role, had defeated the Japanese at Bougainville and Guam. The 5th Division was brand new, but most of its rifle companies were led by former Marine Raiders and paratroopers with combat experience in the Solomons. Moreover, the training focus for each division was right on target for Iwo: small unit tactics, assaults on fortified positions, and coordinated use of combined arms. Col­lectively, this was a tough, combat-savvy landing force, as lethal an amphibious spearhead as the Marine Corps ever had fielded.

Embarking the huge landing force uncovered frustrat­ing problems. The newly modified M4A3 Sherman tanks were now too heavy to be transported safely in standard LCM-3 tank lighters and had to be loaded, five at a time, on medium landing ships (LSMs)—which in turn altered landing plans. The Marines also were chagrined to find that their new TD-18 bulldozers were one inch too wide for the ramps of the LCM-3s, requiring more last-minute adjustments. All hands worried about the 105-mm how­itzers preloaded in amphibious trucks (DUKWs). The weight of the field piece equaled the maximum payload of the craft; rough seas would jeopardize seakeeping ca­pabilities. Amphibious rehearsals reflected the recurring problem of geographic separation of key task groups. Most amphibian tractor (LVT) units did not get the chance to rehearse with the tank landing ships (LSTs), many of which were new to the ship-to-shore business.

Mitscher’s Task Force 58 pummeled mainland Japan, bringing a grim smile to the commander’s wisened face. It had been nearly three years since Mitscher and Fleet Admiral William “Bull” Halsey had launched the last car­rier strike on Tokyo, the daring raid of Jimmy Doolit­tle’s bombers. Mitscher’s active presence in Japanese wa­ters for three days effectively prevented most enemy aerial attempts to strike the amphibious task force at Iwo Jima, just three flight hours away.

The most spectacular exchange of heavy gunfire at Iwo Jima occurred on D-minus-2, 17 February, during the con­duct of the beach reconnaissance by Navy and Marine swimmers. These were men of the Navy Combat Demo­litions Unit, augmented by reconnaissance Marines, col­lectively called “Frogmen." Many were veterans of stealthy reconnaissance missions in the Marshalls, Marianas, and Palaus, but nothing would be covert about this operation: a direct approach into “the bight” in broad daylight. This was a mission of tremen­dous risk, reflecting the critical shortage of information on the landing beaches.

“We didn’t have wetsuits in those days,” recalled for­mer Navy Lieutenant E. F. Andrews, “we just wore swim trunks and a coat of axle grease. Hitting that water at 57 degrees was a real character-builder!” So was swimming 500 yards from the launch boats under the direct exchange of increasingly heavy fire. A dozen LCI (G) gunboats com­prised the first line of fire support for the frogmen, closely followed by several destroyers. Seeing this mini-armada approaching the most obvious beach, the Japanese com­mander believed the landing to be under way and autho­rized his local commanders to unveil their concealed coastal defense batteries along the eastern slopes of Suribachi and the Rock Quarry. The tiny LCI(G)s were shot to pieces; one sank, and all others were badly damaged, with 200 casualties. Lieutenant Rufus G. Herring’s conspicu­ous bravery in extracting his heavily damaged craft from this murderous fire earned him the Medal of Honor. Mean­while, the destroyers and cruisers moved close ashore and engaged the enemy batteries one-on-one, both sides catch­ing hell and delivering same. Incredibly, the swimmers accomplished their mission despite the cannonade, even braving Japanese rifle fire to gather samples of beach sand. They found only one mine, and no obstacles or natural barriers to the approach. Then they retracted with the loss of a single man.

The swimmer mission, accomplished at great risk and acceptable cost, thus served the even more valuable func­tion of an inadvertent amphibious feint, causing the enemy to play his hand prematurely. Blandy’s gun crews had a field day for the next 36 hours, taking out the big guns overlooking the beaches that the Japanese had unwisely revealed. This factor probably saved 1,000 U.S. lives on D-day morning.

Turner had hoped for three days of good weather to conduct the landing. He got one. D-day was nigh perfect. At 0645 Turner signaled, “Land the Landing Force.” The now-familiar choreography began, the process that sometimes proved so difficult at Tulagi or Tarawa now unwinding like a Swiss clock. To some observers, the ship-to-shore assault against Iwo Jima’s southeast coast resembled the third day at Gettysburg: hundreds of thou­sands of men of both sides were watching the panorama of 10,000 shock troops in disciplined alignment charging the center. “The landing was a magnificent sight to see,” said Marine Lieutenant Colonel Robert H. Williams, a reg­imental executive officer. “Two divisions landing abreast—you could see the whole show from the deck of a ship.” Mitscher’s Task Force 58 had returned from raiding Hon­shu in time to add to the fireworks. Among other assets, this provided the landing force with the temporary sup­port of eight carrier-based Marine fighter squadrons, each well-trained in close air support. The troops cheered as the graceful, gull-winged F4U Corsairs with USMC mark­ings roared along the beaches ahead of the landing.

The ship-to-shore movement at Tarawa 14 months ear­lier had featured a convoluted ten-mile trek that took hours and left the LVTs dangerously low on fuel. Worse, the only senior control officer in the lagoon was the skipper of the minesweeper marking the line of departure, who was brave but inexperienced in amphibious execution and unassisted by any Marines. This led the commander of the transport group to comment afterward: “The lack of a di­recting head for troop movements in a position where he could see and take action was keenly felt.” At Iwo Jima, the LVTs had an easy 30-minute run to the beach, and the assistant commanders of the assault divisions, both brigadier generals, took station on the control vessels mark­ing each end of the line of departure.

Without the deadly lapses that characterized Tarawa, naval gunfire support proceeded steadily as the assault waves of LVTs approached the beach. Navy and Marine fighters made one final sweep along the coastline, then the ships commenced a carefully regulated “rolling bar­rage” to provide a moving curtain of heavy ordnance just ahead of the shoreward-bound troops. This complex procedure worked to perfection, reflecting the cumulative experience and painstaking planning of the amphibious task force. A Japanese naval officer observing all this from a cave on Mount Suribachi could hardly believe his eyes: “At nine o’clock in the morning several hundred landing craft with amphibious tanks in the lead rushed ashore like an enormous tidal wave.” About 8,000 Marines stormed ashore in the first few minutes. Within 90 minutes some of these men cut the lower part of the island in two. By dusk General Schmidt had 30,000 men ashore, the better part of two divisions, each with most of their organic field artillery. In between were severe problems with beach con­gestion and extremely accurate fire from General Kuribayashi’s untouched gun positions to the north, but V Amphibious Corps was ashore in great strength and good order.

Trafficability proved worse than expected; even some of the tracked vehicles had difficulty ascending the steep terraces. And though the Japanese had not mined the beach approaches, they had spared no effort in mining beach exits. Many Sherman tanks came to grief in a deadly field of horned antitank mines, inverted depth charges, and naval torpedoes buried vertically beneath pressure detonators.

The steep beach featured a constantly plunging surf and a vicious undertow. Time and again the surf first would broach, then shatter the Higgins boats and LCMs, reduc­ing them to shards and splinters—further fouling a beach that already resembled a demolition nightmare.

By day’s end Schmidt counted 2,400 casualties among the landing force, a stiff price for the beachhead—com­parable to losses of the U.S. V Corps at Normandy’s Omaha Beach on D-Day—but still proportionally better than the first night at either Tarawa or Saipan. When the night came and went without the massive counterattack, Schmidt knew his force was ashore to stay. He also sensed he was facing a formidable opponent, although days passed before his staff could confirm that Kuribayashi had in fact been present on Iwo Jima from the start.

Bad weather the next day severely hampered unload­ing operations. Even the larger landing ships, LSTs and LSMs, had difficulty maintaining position when beached. Stern anchors rarely held. Forward cables to “deadmen” (usually wrecked tanks or LVTs on the beach) snapped under the strain. Smaller craft played hell getting ashore. One artillery battalion commander watched in help­less horror as 12 of his 14 105-mm guns went down in deep water, one by one, when their DUKWs swamped in the choppy seas.

Schmidt’s desire to land a regimental combat team from the corps reserve on D+l could not be met. The troops debarked in a series of hair-raising net-to-boat episodes, then circled for hours, desperately seasick, waiting for the pounding surf to abate on the beach. It never did. The troops had to struggle back on board their transports and wait an­other day. Hill’s efforts to land heavy equipment by pontoon causeway sections proved equally disastrous.

Finally, Hill had to close the beach to all but LVTs and DUKWs.

At this point, the inexpe­rience of some of the LST crews and the absence of any opportunity to rehearse with LVT and DUKW units proved costly. Because of the high surf, wounded Marines could be evacuated from the island during the first several days only by LVT or DUKW, often just at dusk to avoid enemy fire. All too frequently, however, the green LSTs would refuse to accommodate these unfamiliar craft ap­pearing close aboard out of the darkness. When pleas and curses failed to work, the small vehicles only could move further out to sea in hopes of finding a more receptive ship. Too often this resulted in LVTs and DUKWs foundering in high seas at night, usually with a dozen wounded men on board. The landing force lost 88 LVTs to non-combat sinking during the campaign, most of them under such circumstances during the confusion of the first several nights.

In all other respects, from casualty handling to fire-sup­port coordination, the Navy-Marine team functioned smoothly at Iwo Jima. During the four-day fight for Suribachi, U.S. destroyers moved in close to the volcano at night, bathing its cave-pocked slopes with searchlights and blasting anything that moved. Rocket gunboats added great shock and devastation to suspected enemy concentration points.

Both flags raised on Suribachi’s summit on 23 Febru­ary came from supporting ships. The cheers emanating from the sailors at the sight of Old Glory fluttering on that high point were just as prideful as those from the embat­tled Marines ashore. “Hot damn!” exclaimed a Navy pilot over the air control net as he saw the flag go up. “ALL HANDS LOOK AT SURIBACHI!” bellowed Squeaky Anderson over his Beachmaster’s bullhorn. “THERE GOES OUR FLAG!”

The Suribachi flag-raising signaled the end of a chap­ter, but hardly the end of the battle. Ahead lay a full month of additional fighting, combat as savage and relentless as the Marines had ever known. The ships, gunboats, and attack aircraft accom­panied the infantry with fire every agonizing yard north­ward. Each infantry battal­ion included its own naval element—surgeons, corpsmen, chaplains—plus an at­tached naval gunfire control party and an air liaison party. Navy Seabees landed in force, an entire brigade, and began rebuilding Iwo’s vital airfields, under fire from day one. Once the surf subsided the amphibious task force landed the 3d Marine Division (less the 3d Marines) in good order.

On 4 March the first crip­pled B-29 landed on Iwo’s still-unfinished airstrip. On 17 March, Smith declared the island essentially secure (drawing derisive profanity from the Marines still fighting and dying in the north) and left the area. The battle in Kuribayashi’s “Bloody Gorge” continued until the 26th, when Schmidt announced the end of enemy resistance and began backloading his corps. The Marines and their naval elements suffered more than 24,000 casualties (actually 27,000 when battle fatigue cases are included). An estimated 22,000 Japanese died de­fending Iwo Jima; fewer than 1,000 became prisoners.

In effect, Iwo Jima was a 36-day amphibious assault. “The size and terrain of the island precluded any Force Beachhead Line,” reported Smith. “It was an operation of one phase and one tactic . . . frontal assault.” The fact that the amphibious task force stood by and delivered combat support throughout much of this protracted assault reflects how thoroughly the fleet had isolated the objective. Leav­ing so many thin-skinned amphibious ships tethered to an island that close to Japan for such a period would have been unthinkable even the year before. Certainly, none of the veterans of Bougainville would ever forget the sudden fury with which Japanese air and surface units came boiling down from Rabaul to strike the amphibians at Em­press Augusta Bay.

At Iwo Jima, however, the Fifth Fleet's picket screens and combat air patrols experienced few difficulties in intercepting aerial counterattackers. There were two ex­ceptions. The night before D-day, a pair of Japanese combers penetrated the task force and struck the attack transport Blessman (APD-48). Ironically, this was the mother ship for the Navy Combat Demolition Teams, the men who had just executed their bold mission so successfully along Iwo Jima’s beaches. The ship survived the attack—the bomb just missed the after hold where the frogmen stored their explosives—but the unit lost more of its members in this one fiery instant than the total of all their combat operations in the Pacific.

At twilight on D+2, a flight of 50 kamikaze planes from the 2nd Mitate Special Attack Unit took off from Katon airbase near Yokosuka and successfully penetrated the Fifth Fleet’s screen. In desperate action that foreshadowed the coming Okinawa campaign, the ships managed to hit all 50 planes, but some crashed into the escort carrier Bismarck Sea (CVE-95), sinking her, and the old warhorse carrier Saratoga (CV-3), damaging her enough to send her back to the States. No other breakdowns occurred in air defense.                                                                    

The once-mighty Combined Fleet made no serious move toward disrupting the Iwo landing. In operational terms, the Japanese Navy’s only contribution was the dispatch of several kaiten “human torpedoes" embarked on fleet submarines. Three of these subs left Kure for Iwo during 22–23 February, followed by two more on 2 March. None got through. The destroyer escort Finnegan (DE-307) sank one sub, aircraft from the escort carrier Anzio (CVE-57) got another; other screening ships kept the remainder well clear of the objective area.

Spruance ordered Mitscher’s Task Force 58 to leave Iwo and pursue more strategic targets after the third day of the battle. The amphibians watched them go with misgivings, appreciative of their greater role in attacking Japan, but rueful over the loss of those beautiful new battleships and the Ma­rine fighter squadrons embarked on the fast carriers. The escort carriers under Rear Admiral Calvin T. Durgin picked up the close air support mission, but it was a tough act to follow. Some of the Marines complained that the escort car­rier pilots did not carry enough large bombs (500 pounds and larger), which was true, and were ineffective with na­palm bombs, which was unfair, since those munitions at that stage rarely averaged a 50 percent detonation rate, regardless of who dropped them. One division commander, who at first suggested the Navy planes be replaced by Seventh Air Force bombers, later changed his tune, reporting “total satisfaction with fleet air support.” Most Marines developed an abiding appre­ciation for any aviator intrepid enough to undertake close support missions in that prolonged and point-blank battle.

Among the most unusual missions provided by the ver­satile escort carrier pilots was that of pest control. With some 80,000 men of both sides locked in mortal combat on a very small island, sanitation became a real problem, and flies appeared everywhere. Navy pilots flew several missions to spray “Dog Dog Tare (the chemical DDT) over the front lines at dangerously low altitudes. "I felt like a damned crop-duster," said Navy Lieutenant David J. Conroy, who flew three such missions off the escort carrier Makin Island (CVE-93) in a torpedo bomber. “Some of the troops would strip to the waist and rub the stuff over their bodies.” The corps surgeon hailed these spraying operations as “a refinement of modern military sanitation.”                                                                     

Nowhere was the Navy’s role in the Iwo Jima battle more crucial than in sustained medical support. Surgical teams operated around the clock in field hospitals barely two miles behind the lines. A dozen women, Navy flight nurses, served on board DC-3s making daily runs to Iwo during the fighting to help evacuate nearly 2,500 wounded men directly to Guam. But this was an extremely costly battle for the surgeons and corpsmen who accompanied Marine units. Exactly 850 of these men were killed or wounded at Iwo Jima, twice the rate for bloody Saipan. Four of the seven Medals of Honor awarded to Navy corpsmen during World War II originated at Iwo Jima. Twenty-two Marines received the Medal of Honor. Half of the awards were posthumous.

The high number of U.S. casualties sustained at Iwo Jima continues to generate post-battle controversy. Some retrospective analysts point to excessive losses among the landing force at Iwo Jima as an indictment of the whole concept of amphibious warfare. This holds no water.

Iwo Jima was in fact the pinnacle of applied amphibious expertise in the Pacific. No analyst should be shocked by the 30 percent casualty rate sustained by the landing force. “It is not the nature of amphibious war to be bloodless," observed Captain John P. Kelly in a Proceedings essay 40 years after Iwo Jima. No one in February 1945 expected a bloodless landing on that highly fortified island, the first piece of Japanese territory to be invaded in the war. The U.S. casualties did not represent a failure of doctrine, planning, or execution. They were the direct result of an imaginative, desperate defense by the gifted Gen­eral Kuribayashi and his disciplined garrison. Yet de­spite Iwo’s daunting natural and man-made defenses, the amphibious task force achieved its two strategic objec­tives in the first 14 days: the B-29 campaign received a tremendous boost; Okinawa’s eastern flank was fully se­cured. Working within a naval campaign, U.S. forces had taken a giant step toward ending the war.