by Daniel Wrinn
Only two significant Japanese capabilities remained: they could reinforce Peleliu from Babelthuap and bitterly resist from their cave positions.
The Allied encirclement of the Pocket suffered from a lack of reinforcements.
The III Amphibious Corps reserves were fully committed to the seizure of Angaur. The Angaur operation’s planning and timing were heavily affected by the Peleliu operation. Division planners proposed landing on Angaur before Peleliu, but General Julian Smith said that would cause the Japanese in northern Palau to reinforce Peleliu.
Division agreed that Angaur should only be assaulted after the landing on Peleliu was sure to succeed. But in the end, the assault on Angaur began before the Peleliu landing was resolved. The 81st Division’s commanding general wanted to land as soon as possible and was supported by Admiral Bill Valenti. General Julian Smith argued that committing the III Corps’ Reserve before the operations on Peleliu were more fully developed was premature and costly. Admiral Wilkinson ignored his advice.
On September 17, the III Corps’ final reserve was assigned to the Western Attack Force and ordered to use “all available forces.” Against General Smith’s advice, Wilkinson committed the entire 323rd RCT and the 81st Division’s other maneuver element. The 321st successfully occupied an undefended Ulithi, while reserves were desperately needed on Peleliu.
By September 20, the 81st Division had destroyed or cornered Angaur’s 1,400 enemy troops, and Anguar was declared secure. The 322nd RCT would complete mop-up operations, and the 321st RCT was now available for further operations.
General Rupertus believed his Marines could do it without help from the Army. The III Corps’ plan had the 81st Division reinforcing Marines on Peleliu and then relieving the 1st Marine Division for the mop-up. But General Rupertus refused to accept the help and continued to tell his commanders to “hurry up.”
Rupertus also shrugged off suggestions from 5th Marines “Bucky” Harris that he should take a look at the Pocket from the newly available light planes of the Marine Observation Squadron 3. Harris’ newest aerial reconnaissance on September 19 changed his view of the Pocket from sober to serious. He believed attacking the Pocket from the north would be less costly than the original plan, and Rupertus told Harris that he had his own map.
The Marines’ plan was built on the tactical concept that the 1st Marine Division would push in a northern line across the island’s width after capturing the airfield. Once close to the southern edge of the Pocket, Marines would advance in four west-to-east phase lines. It was expected that the advance along with flatter zones east and west of the Pocket would be roughly the same pace as along the high central ground of Peleliu. Maybe this thinking was consistent with Rupertus’ prediction of a three-day assault, but developments in Marine sectors to the west and east didn’t change division-level thinking. Until additional forces were available, this linear advance may have seemed the only possible advance.
There was no re-examining the planned south-to-north advance, and for days, the Pocket was sealed off at its northernmost extremity. Still, the division commander kept ordering attacks from south to north following the initial landing plan. As “Bucky” Harris reported from his aerial reconnaissance of the overall Pocket, these attacks would only bring severe casualties. Heavily supported Marines could advance into “the Horseshoe” and “Death Valley,” but their positions would soon prove untenable, and they’d need to withdraw by day’s end.
The failure in this thinking may have come from the mapping use. The 5th Marines in early October created a newer sketch map to locate and identify the details within the Umurbrogol Pocket.
Even after General Geiger had ordered General Rupertus to stand down Puller’s shattered 1st Marines on September 21, Rupertus made it known that his Marines alone would clear the entire island. After taking a closer look at the situation on the ground, General Geiger ordered the 321st RCT from Angaur and attached them to the 1st Marine Division—the encirclement of the Umurbrogol Pocket was possible.
Capturing Ngesebus and northern Peleliu became a priority. Allied forces discovered on September 23 that considerable enemy troop strength in the northern Palaus was being ferried by barge from Koror and Babelthuap. Even though the Navy patrol set up to protect against those reinforcements had discovered and destroyed some of the Japanese barges, many enemy troops had waded ashore on the early morning of September 23.
Colonel Nakagawa now had reinforcements on northern Peleliu.
Northern Peleliu Seizure
General Rupertus held a meeting with III Corps staff and General Geiger. They formed a plan to encircle the Pocket and deny reinforcements to the enemy on northern Peleliu. The Army’s 321st Infantry would advance up the West Road with the 5th Marines. After they reached the Pocket, Marines would pass through Army lines and continue north to assault Ngesebus and northern Peleliu.
The 321st Army Regimental Combat Team was now a battle-tested and hardened outfit. They would advance up the West Road along the edge of the elevated coral plateau. The plateau was 300 yards west to east and formed the western shoulder of the Pocket. It rose seventy feet, and its western cliff was a jumble of small ridges that dominated the road. This cliff would have to be cleared and secured to allow for an un-harassed use of the road.
After the 321st passed this cliff, they could probe east in search of any routes to the eastern edge of Peleliu. Any openings in that direction would be a chance to encircle the Pocket on the north. Following the 321st, the 5th Marines would press their attack into northern Peleliu. The 7th Marines (relieving the 1st) were stood down on the eastern peninsula and relieved the 5th Marines of their passive security role. This allowed the 5th to focus on the capture of northern Peleliu and Ngesebus.
The West Road would be used as a tactical route north and then as a communication line for continuing operations. The road was paralleled by the jagged cliff, which made up the western shoulder of the plateau. This was not a level plateau and had a moonscape of sinkholes, coral knobs, and karst.
With no defined ridges or patterns, the sinkholes varied from room size to house size, and some were over twenty feet deep and covered by jungle and vines. This plateau was ninety feet above the road. And another 300 yards to the east, it dropped off into a sheer cliff (known as the China wall). Marines who looked up at it from the eastern approaches to the Pocket claimed the western edge of the plateau was “virtually impassable.”
The plateau was also impenetrable to vehicles. Coral sinkholes forced all infantry to crawl, climb, and clamber into small compartments of jagged and rough terrain. Having to evacuate any casualties would involve rough handling of stretchers and the wounded men.
The enemy defended this area with scattered small units who bitterly resisted movement into their moonscape. Japanese troops ignored individuals and only fired on groups or what they considered rich targets.
The tactical decision along the West Road was to seize and hold the cliffs and coral spires. From here, they could command the road and defend these positions against any attacks. Once these heights were secured, troops and trucks could move along the West Road. But until secured, this cliff gave cover and concealment to the enemy. Until these cliff positions were taken and held, the Japanese could only be temporarily silenced from heavy firepower.
On September 23, this was the situation the 321st launched their assault into. Following an hour-long naval bombardment against the high ground of the West Road. Army patrols moved in and were screened from the Japanese still on the cliff. These small-unit tactics worked well until larger units of the 321st moved out alongside the West Road. From here, the enemy unleashed hell from above.
Two battalions of the 321st advanced along an east-west line across the road and up to the heights. Soldiers secured the west edge of the cliff and advanced northward, but some elements of the cliff were outpaced to the west. Instead of fighting to seize the ridge, some units responsible for securing the cliff abandoned it and side-stepped d
own to the road.
Colonel Hanneken ordered the 3/7 to capture the high ground that the 321st had abandoned. After that, the 3/7 Marines were committed along the ridge within the 321st zone of action. This stretched the Marines, who still needed to maintain contact to their right. Farther north, the 321st pressed on and regained some of the heights above their advance and held onto them.
On the northern end of the Pocket, the sinkhole terrain blended into regular ridgelines. The 321st assaulted Hill 100, along with a nearby hill east of East Road, and designated it Hill B. This position was the northern cap of the Pocket. The 321st would fight for Hill B and the northern cap of the Pocket for the next three days.
The 321st probed the eastern path across the north end of the Pocket. They sent patrols north up to the West Road. In an area of buildings designated “radio station,” they found the junction of East and West Roads. Colonel Bob Dark, commanding the 321st, sent a mobile task force (Task Force Neal), heavy with flamethrowers and armor, to circle southeast and join with the 321st at Hill 100. Below that battle, the 7th Marines continued to put pressure on the south and east fronts of the Pocket.
As this was underway, the 5th Marines were ordered to help in the battle for northern Peleliu. The 5th motored, marched, and waded to the West Road and sidestepped the 321st to join in the fight. The Marines found flat ground, some open, and some covered with palm trees. The familiar limestone ridges broke the ground. But the critical difference here was that most of the ridges stood alone.
Marines were not exposed to flanking fire from parallel ridges like they were in the Pocket. The Japanese fortified the northern ridges with extensive tunnels and concealed gun positions. But these positions could be attacked individually with flamethrowers, demolitions, and tank tactics. Many of the enemy defenders were from Naval construction units and not trained infantrymen.
On the US side of the fighting, Colonel “Bucky” Harris was determined to direct all available firepower before sending his infantry into the fight. His newer aerial reconnaissance gave him a better understanding of the terrain.
On September 25, the 1/5 Marines secured the radio station complex. When the 3/5 arrived, they were ordered to seize the next high ground to the east of the 1/5’s position. From there, they would extend the regimental line back to the beach. This broke contact with the 321st’s operations in the south but fulfilled Colonel Harris’s plan to advance north as rapidly as possible without overextending their lines.
By suddenly establishing this regimental beachhead, the 5th Marines had surprised the enemy with powerful forces in position to engage them fully in their cave defenses the next day.
5th Marines Northern Attack
On September 26, the 321st launched a three-pronged attack against Hill B. The 5th Marines attacked the four hills running east to west across Peleliu (Hills 1,2,3, and Radar Hill). This row of hills was perpendicular to the south of the last northern ridge—Amiangal.
These hills were defended by 1,500 enemy infantry, artillery, naval engineers, and the shot-up reinforcing infantry battalion, which landed on the night of September 23. The enemy were well protected in the caves and interconnected tunnels within the hills and ridges.
As the fighting started, Colonel Harris side-stepped his 2nd Battalion west of the hills and attacked Amiangal Ridge to the north. By dark, the 2nd Battalion had secured the southern end of the ridge but took heavy fire from positions in the central and northwestern slopes.
The Marines now confronted the most wide-ranging set of tunnels and caves on Peleliu. They were trying to invade the homes and defensive positions of a long-established naval construction unit. Most of whose members were better miners than infantrymen. As night settled, the 2nd Battalion cut itself loose from its southern units and formed a small battalion beachhead for the night.
The next morning, the 2/5 Marines tried to advance along the route leading to the northern nose of Amiangal Ridge. They ran into a wide and deep anti-tank ditch that denied them the close tank support they’d successfully used earlier. Again, the 5th Marines asked for point-blank artillery.
This time division responded. Major George Hanna’s 155mm Gun Battalion moved one of its pieces into position. This gun was 175 yards from the face of the ridge. The sight of that gun prompted enemy machine-gun and small arms fire, inflicting casualties upon the artilleryman.
Enemy fire was quickly suppressed by Marine rifle fire and then by the 155mm gun. Throughout the morning, the heavy 155mm fire pounded across the face of the ridge and destroyed or closed all identified caves on the west face—except one. That cave was a tunnel mouth that led down to the ground level in the northwest base of the hill. It was too close to Marine lines to permit the 155mm to fire on it.
After a bulldozer filled in a portion of the anti-tank ditch, tank-infantry teams moved into blast and bulldoze the tunnel mouth closed. Marines swept over the slopes above the tunnel and secured the crest of the northern nose of Amiangal. While Marines held the outside of the hill, stubborn Japanese defenders still occupied the interior.
A maze of interconnected tunnels extended throughout the length of the small Amiangal mountain. Enemy defenders would blast open the previously closed cave or tunnel mouth and surge out in a banzai attack. Apart from the surprise, these counterattacks were a rare and welcome opportunity for Marines to see and kill their enemy in daylight. These tactics were inconsistent with the overall enemy strategy on Peleliu and shortened the fight for the island’s northern end.
As the fighting raged on, the 5th Marines assembled its 3rd Battalion with supporting tanks, amphibian tractors, naval gunfire, and air support to assault and secure Ngesebus 700 yards to the north of Peleliu on September 28.
This operation involved a single, reinforced battalion against 500 prepared and entrenched enemy infantry. In just over forty hours, the 3/5 Marines fought the most cost-effective single battalion battle in the Peleliu campaign.
Seizure of Ngesebus
The 3rd Battalion got ashore with no casualties. They immediately knocked out all the enemy’s beach defenses. Then they turned their attention to the cave positions in the ridges and blockhouses. The ridges here were like those in northern Peleliu in that they stood individually and not part of a complex ridge system.
This denied enemy troops the opportunity to have a mutual defense between cave positions. The attacking Marines could use supporting tanks and concentrate all their fire on each defensive system—without taking fire from their flanks.
By dusk on September 28, the 3/5 Marines had overrun most of the enemy opposition. The next day at 1500, Ngesebus was declared secure. The island was turned over to the 321st, and the 3/5 Marines were put into the division reserve.
The seizure of Ngesebus by one depleted infantry battalion illustrates an enduring principle of war: effective concentration of means. General Rupertus concentrated all his available firepower: divisional and corps artillery, two cruisers, a battleship, nearly all the division’s remaining armor, armored and troop-carrying amphibian tractors, and all Marine aviation on Peleliu.
This concentrated support allowed the heavily depleted 3/5 Marines to secure Ngesebus and destroy 477 of Colonel Nakagawa’s battle-hardened, entrenched soldiers in forty-one hours at the cost of forty-eight Marine casualties.
As the 3/5 Marines were securing Ngesebus, the rest of the 5th Marines fought the Japanese still hunkered down in northeast Peleliu. After seizing Akarakoro Point past Amiangal Mountain, the 2/5 Marines turned south and swept through enemy defenses east of the mountain with flamethrowers and demolitions. Then they moved southward to Radar Hill, the stronghold of Hill Row.
Radar Hill was under attack from the south and west by the 1/5 Marines. After two days, two battalions were on the top side of the hills. But inside, there were still stubborn enemy defenders continuing to resist.
Marines solved this problem by blasting the cave and tunnel mouths closed—silencing the enemy forever.
Fight for th
e Pocket
The Umurbrogol Pocket was the scene of the bloodiest and most costly fighting along with the campaign’s best and worst tactical decisions.
Its terrain was the most challenging on the island. Pre-landing planners didn’t realize the Pocket for what it was: a complex cave fortress perfect for a suicidal defense. The southern slopes (known as Bloody Nose) dominated the landing beaches and airfield through where the Pocket had to be assaulted.
After Colonel Puller’s 1st Marines conquered those heights through a costly and brave assault, command sent in artillery controlled by aerial observers. This radically changed the situation. The Pocket’s defenders could only delay and harass Allied forces with sporadic fire attacks and nighttime raids. After D +4, enemy defenders in the Pocket could no longer seriously threaten the division’s mission.
After more enemy observation sites were secured, General Rupertus continued to urge his Marines forward. He pressed his commanders to keep up momentum. As though the seizure of the Pocket was as crucial as securing the commanding heights guarding it from the south. But the challenging terrain and fanatical defenders became entangled with Rupertus’ determined character.
This was only sorted out by time and the intervention of General Geiger. Most of the offensive into the Pocket between September 21-29 was directed into the cave mouths, ridges, and twin box canyons. Infantry, tanks, air support, and flame-throwing LVTs penetrated the low ground but were then surrounded on three sides. Enemy positions inside canyons and ridges were hidden from observation. Japanese troops were protected in their caves and were skilled at making the captured low ground untenable.