The Battle For Peleliu - "Hell's Cauldron"

William H. Stewart, Military Historical Cartographer
    In early l944, the Palau Islands were subjected to numerous air attacks as the American forces pressed west toward the Japanese in the Philippines. The principal targets were  the naval and military headquarters on  Koror, the port at Malakal, the air base at Peleliu and the seaplane base on Arakabesang Island. Targets on Babelthaup were the radio stations at Airai and Ngatpang, and other military installations in the southwest part of the island.  The biggest strikes, prior to the invasion of Peleliu and Angaur, were made on March 30 and 31, when a number of Japanese vessels were sunk in the vicinity of Malakal Harbor. During this strike, naval and shipping facilities were badly damaged and l60 Japanese aircraft were destroyed.

    On September 15,1944, an assault on Angaur and Peleliu was made to secure the U. S. approach to the Philippines from bases in  New Guinea.  The invasion was undertaken by the Third Amphibious Corps of which the major components w ere the 1st Marine Division and the 81st Infantry Division.  The 1st Marine Division's personnel of 17,490 was augmented by 10,994 from the 81st. to bring the total to 28,484 men.

    The invasion was preceded by the work of underwater demolition teams which cleared approaches, and by nearly three days of heavy naval bombardment. 

Before the invasion, when this preparatory bombardment began, the commander of naval fire support optimistically reported he "would run out of targets before D-Day".  Unfortunately, he was highly incorrect.  Fire support was provided by the battleships Maryland, Pennsylvania, Idaho  and Mississippi, and the cruisers Louisville, Honolulu, Indianapolis and Portland. Installations above ground were severely damaged, but many entrenched positions, particularly those within caves, were left untouched.  The assault was made on the beaches on the west side of Peleliu, across a reef flat averaging 700 yards in width.  From the transfer point beyond the reef, waves of LVT (A)'s (Landing Vehicle, Tracked, Armored, "amtracts"), and DUKW's (2 1/2 ton, 6 by 6 amphibian trucks known as "duck's") made their way across the reef to the beach, accompanied after the third wave by waterproofed Sherman medium tanks.  Eighteen American tanks were sent toward shore on D-Day to support the  1st Marine Division and all but one were hit.  Three were stopped before they could make it to the beach and six more were lost ashore during the early hours of the fighting against Colonel Nakagawa's l4th Manchurian Division.


    The Japanese l4th Division, with headquarters on Koror, constituted the principal defense force for the Palau Islands. The force, with auxiliary troops, numbered about 25,000, with the greatest number stationed on Babelthaup.  On Peleliu the 2nd Regiment composed the principal defense force. In all,there were approximately 5,300 army and 1,000 naval combatants, 2,200 navy airbase personnel, and 2,000 navy laborers, totaling 10,500.  The U. S. Navy effectively denied the Japanese the overwater approaches to Peleliu.  Heavy Japanese losses were sustained during attempts to bring in reinforcements from the north by barges.  However, the Japanese did not commit themselves extensively to the reinforcement of Peleliu, as they assumed a major attack on Koror and Babelthaup would follow.  It never did.

     American losses on the reef and beaches were heavy.  Once inland, good advances were made. However, the coralline rubble and rock composing the ground, although suitable for the development of prepared positions, usually did not permit quick entrenchment, and the foot soldier had little cover while advancing or holding his position.

    The airfield, the one open level area which favored tank operations, was overrun by the second day and all but the northern peninsula of the island was taken by the end of the first week.  The two month siege which followed tends to obscure the fact that the basic mission was accomplished within one week.

The  air field was made operational, all the beaches necessary for the landing of supplies were in use, and the development of the island as a base was begun.  Beachheads were established on the northeast coast and on the north end of the southeast coast.  Organized resistance ceased on September 20th, but some Japanese held out for a longer period of time in the rugged limestone pit and pinnacle terrain in the northwest corner of the island.  The taking of the north peninsula was slow and costly. The Japanese had enlarged caves in the coralline limestone and dug tunnels, some with multiple entrances. The parallel arrangement of ridges made many of the positions mutually supporting.

     An advance was made along the coastal plain, and the tip of the peninsula was reached on September 27th.  From here Ngedbus Island containing a minor airstrip and the semi-connected island of Olngeuaol (Ngaregeu or Kongaru) were taken the following day.  After seizing "Radar Hill", the knob  at the southeast corner of the isolated group of hills at the  northeast end of the peninsula, a drive was made back to the Umurbrogal Mountain stronghold at the southwest end of the peninsula which was surrounded by October 3rd.  The Japanese resistance north of the airfield had been bypassed and the northern end of the island along with Ngadbus and Kongaru Islands were taken by the 5th Marine Regiment.  The remaining Japanese were encircled and compressed so that all major resistance was overcome on October 13,1944.  All that remained was to disgorge the Japanese defenders from a network of fortified caves.  An ominous task that would prove to be very costly.


    Rough, bouldery terrain was smoothed to allow access by American tanks and LVT's.  Artillery was fired point-blank into cave entrances and other defensive positions, but in many cases the rough terrain did not permit placing the artillery into suitable firing positions.   

    Flame throwers, mounted on LVT's and afterward on tanks, were placed at considerable peril when positioned to throw their fire effectively.  Against caves, the flame throwers had the advantage of greater penetration as their effect carried into cave bays and around corners immune to shell fire.  Flame throwing tanks would project their burning rod of chemical death some 140 to 150 yards into the caves.  Another method used to clear caves of Japanese defenders was to use Sherman tanks to fire several rounds of white phosphorous shells into a cave. This would force the Japanese to put on gas masks and run out of the cave to be cut down by machine gun fire. Perhaps the shortest bombing runs in history were made by American planes taking off from the Peleliu field.

Before they could raise their landing gear, their bombs were dropped on the ridges which began a few hundred yards north of the field. Explosives and napalm were used, but against the underground defenses in the Umurbrogol pocket these had little effect. The Japanese made few suicidal "Banzai" attacks. Mass fire of any sort became impossible as distances became short and instances occurred in which American troops held the base and top of a ridge while the Japanese held the steep slope by means of their underground defenses. The details of the peninsular ridges were not accurately shown on the available maps and target designation was difficult.

    The permanent relief of the 1st Marine Division by the 81st Infantry Division began on October 15th.  The siege of the pocket continued for six weeks longer  with slow, methodical advances.  Sand bags came into important use to protect positions gained so they could be held. The "Horseshoe", a box valley extending northeast from the southeast corner of the peninsular ridge mass, was flooded with light at night to reveal Japanese attempting to get water from the pond, their only important source of fresh water.  At one time a pipeline complete with booster pumps and  nozzle led 300  yards from a fuel truck to a point where its flame could be sprayed  on Japanese positions like water from a hose.  Conveyor systems were improvised to get supplies to ridges and to evacuate the wounded.  A ramp of coralline rubble was completed from the floor of "Wildcat Bowl", the next valley northwest of the "Horseshoe", to enable tanks and an LVT flame thrower to reach the ridge crest.  The last-held enemy cave area was situated in the "China Wall" forming the northwest side of "Wildcat Bowl".    


    The Japanese use of caves to defend Peleliu provides a classic example of the use of terrain to the utmost military advantage.These static defensive shelters, however, had the disadvantage of making  communication and organization difficult between the individual  Japanese positions: Three general types of caves are found on the island: artificial caves, entirely natural caves and improved natural caves.

Artificial caves are further distinguished between those constructed by the Navy and those by the Army.  Navy caves were usually tunnels approximately ten feet wide and six feet high with a series of rooms for storage of supplies and living quarters.  They were formed as "H", "E", "Y", "T", "I", "L" and "U" shaped.

    Army caves were usually combat positions and storage depots and almost always natural caves.  Very few had escape tunnels but frequently had protected interior passages for use once the entrance to the cave was either lost or sealed. Generally, these  caves are located on the lower half of ridges on all sides of the hills.  Their sloping floors were not designed for protection against attacks using liquid weapons such as gasoline and oil which would be poured or pumped into the cave-drain down to the lowest level - and then ignited. 

Unlike the caves used by the Japanese Navy, Army caves were usually smaller, more numerous and often interlocked with pillboxes and communication trenches. 

Improved natural caves can be distinguished  by modifications made to enhance their military usefulness. Stalagmites were removed and floors leveled, hanging rocks and stalactites were chipped away, the entrances were camouflaged and connecting tunnels dug between other caves.  Various cave levels can be found joined by natural cavities.  Caves used for storing supplies required less improvement than others.

    There are three types of natural caves on Peleliu: "water cavities" formed by erosion by subterranean streams - these were virtually invulnerable to direct fire and flame throwers; "balcony caves" which provided excellent positions for snipers and machine guns located high on the ridges; and "vertical fault type caves" which were usually larger than the other types of caves. Many vertical fault caves served as living  quarters complete with communication equipment and electricity.  One such cave was attacked with every available type weapon, except the mobile flame thrower which could not traverse the difficult terrain.  Finally, as a last resort, the entrance had to be plugged with cement by the U. S. Marines.  Still, water and air seepage, combined with food stored there-in enabled the entombed Japanese to live in it long after it had been sealed.  As an example of Japanese ingenuity and tenacity, water seepage into caves was controlled, and an ample water supply provided by tying pieces of string to the numerous stalactites and leading these strings down into a water barrel for storage.


    For the Americans fighting on Peleliu there was no other combat to compare with it up to this point in the Pacific war.  The cave fighting on this island was unique in the annals of military history.  The northern and western portion of the island consisted of an irregular series of broken cliffs, narrow valleys studded with natural cavities and jagged crags. There are rugged peaks and, in some areas, an impenetrable mass of sheer walls.  While the general formation runs north and south, small ridges and valleys run in every direction within.  The maze of hills extend only some 3 1/2 miles in length and are no wider than 300 to 700 yards from the point on the western side of the island where the elevation from sea level becomes perceptible.  The hills then rise to a height of 200 to 225 feet and then fall away eastward to mangrove swamps and dense tropical vegetation at sea level.  Rock edges are razor sharp and natural faults and fissures are  50 feet deep in some places.  Within this landscape some 300 natural and 200 artificial caves - many dug as a result of earlier Japanese phosphate mining activity - were strongly fortified.  Add to this the decayed coral strewn about with rubble, crags, ridges and gulches in a confusing maze - the extreme heat of the tropical climate; insects of every conceivable variety; damp jungle and mangrove swamp; torrential rains; a deadly adversary willing and anxious to die for his country - and you have the recipe for a nightmare.


    Marine Corps General William Rupertus scheduled operation Stalemate II for September l5, l944 and expected the 4.7 square mile island to be secured within four days.  Colonel Kunio Nakagawa and his forces were not so cooperative...the fighting continued until November 27th, sixty nine days longer than anticipated.  On the morning of November 27th, infantry men moving north along the ridge of "China Wall" met their comrades coming southward, and the battle was over.During the fighting five hospital ships off shore from Peleliu removed

2,343 American wounded during the early days of the fighting.  At Kossol passage, some 70 miles north of Peleliu, the U. S. Navy swept the area for mines, buoyed and netted the waters for use as a sea plane base and to harbor supply ships which were waiting to unload their cargo at Peleliu when called upon to replenish the supplies of the invading forces. 

     "Earthenware", Peleliu's U. S. military code name, was unusually fitting in a macabre sort of way, for the island and its temporary oriental and occidental occupants were ground unto dust and baked in a cauldron of fire, steel and stone.  Deep inside the sealed caverns those Japanese that did not die of burns from phosphorus grenades lobbed through entrances to ignite oil which had been poured inside, succumbed to starvation, suffocation, concussion and utter depression.  In the dark, damp interior, their remains disintegrated into dust entombed within the bowels of the mountains of Peleliu.  They are still there.

    With the exception of Peleliu and Angaur,the remaining islands in Palau were surrendered on September 2, 1945- the day Imperial Japan surrendered- by Lieutenant General Sadae Inoue to Brigadier General F. P. Rogers, U. S. M. C., Island Commander Peleliu aboard the U. S. S. Amick (DE168). Troops surrendered in Palau totaled 34,773 (Army 18,493; Navy 6,407 and labor personnel 9,873). 

These were the troops which had been stationed at Koror and Babelthaup, islands which had been bombed and by-passed after the fall of Peleliu and Angaur.

    Some historians believe the battle for Peleliu was unnecessary.  Prior to the invasion of the Philippines, Admiral Nimitz wanted to remove any threat from Peleliu to General MacArthur's right flank during the assault on that former American territory and secure a base from which U. S. forces could support the Army General's invasion of the Philippine Islands.  However, Peleliu did not prove to be such a valuable military asset and was largely unneeded during the Philippine operation.

       When the islanders did return  after the fighting-(they had been relocated by the Japanese to the island of Babelthaup prior to the invasion)-they were appalled at the conditions they found.  The devastation caused by the savage fighting, fierce shelling and intense bombing had changed the contours of Peleliu's topography.  Trees had either been blasted away or stripped bare. 

The vegetation on the hills had been burned away by napalm revealing the barren, jagged hills.  The rubbish of battle was strewn across the landscape and the remains of the Japanese dead were being bleached white by the unrelenting equatorial sun.Flies, maggots and flesh eating rats were every where.


    The casualties of the American forces numbered 1,039 killed; 5,142 wounded and 73 missing in action.  The Japanese suffered  10,937 killed and 2,500 taken prisoner.  The ratio of Japanese to American dead was 10 to 1. Two years after the fighting a ragged platoon of hideouts surrendered upon the loudspeaker exhortation of a Japanese admiral brought to Peleliu to plead with them. No one knows how many were buried alive and remain sealed in caves to this army of skeletons and rusting weapons defending their tomb in the Umurbrogal Mountains as the last remnants of the Imperial Japanese Army.  It took a statistical average of 1,589 rounds of heavy and light ammunition to kill a Japanese soldier on Peleliu. This does not include the shelling from a three day naval bombardment by the U. S. Navy and bombing from American bases in New Guinea.

    Interestingly, the Japanese at Peleliu did not direct their artillery fire at the U. S. troop transports stationed offshore. Had they done so, U. S.

casualties would have been far greater.Peleliu was made into an important U. S. airbase for the Navy and Angaur for the Army.  Both were used in the operations against the Japanese in the Philippines. At the end of the war, all Japanese and Koreans were repatriated.  Koror had been extensively bombed, and before these survivors departed they were directed to  tear down and clean up the debris.  Little was left of Koror to indicate that it had been a pleasant tropical town of some 15,000 inhabitants.  Peleliu and Palau slowly slipped out of focus during the ensuing years only to re-emerge a quarter of a century later as being of strategic importance once again to the United States Navy in the western Pacific.  Today, a dead fleet of U. S. landing craft rests and rusts on Orange Beach caught in the belligerent pose of 1944, half in and half out of the water as if still struggling to make it ashore. Twenty six Japanese stragglers were found still alive on Peleliu two years and eight months after the war ended  on September 2, 1945.  On Guam, a straggler was found hiding in a cave more than 25 years after the conclusion of hostilities.  Who knows...there may be survivors of the Imperial Japanese Army still alive on some remote island and could conceivably remain until about the year 2008 when a 19 year old Japanese soldier in 1944 would reach 83 years of age.


Sources:  Know Your Enemy, CICPOA, U. S. Navy Bulletin #173-45; Operations Against Peleliu,  Col. H. D. Harris, U. S. M. C., Army and Navy Staff College Lecture, Washington, l945 ;Military Geology of Palau Islands, Chief of Engineers, U. S. Army, 1956 ;  Conversations with Mr. Yuki Shmull,  former Governor of Peleliu and Mr. Koichi L. Wong, former Minister of National Resources; Allied Translator And Interpreter Service, U.S. Army In World War Two, The War In The Pacific- Guadalcanal --The First Offensive- Historical Division, U.S. Army, The Pentagon, Washington, D.C.