by Daniel Wrinn
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 down 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.
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 the 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.
Other attacks to seize the heights of the eastern ridges were initially successful. Small infantry units scrambled up onto the bare ridge tops but came under fire from facing parallel ridges and caves. They were also harassed by strong enemy counterattacks who left their caves under cover of darkness in suicide attacks.
On September 20, the 7th Marines relieved the 1st Marines along the southwest front of the Pocket and resumed the attack the next day. These assaults achieved limited success behind heavy fire support and smoke. But these positions became impossible to maintain after the fire support and smoke lifted. Assault troops were withdrawn under renewed fire support to their original jump-off positions. There was little to show for the day’s bloody fighting.
On September 22, against the west shoulder of the Pocket (Wildcat Bowl), Allied troops gained ground on their early advances—most of which were surrendered at day’s end. Marines came under heavy fire from concealed defenders in their mutually supporting cave positions. The 7th Marines had advanced to within a hundred yards of Colonel Nakagawa’s cave position. But several supporting hilltops and ridges would have to be reduced before a direct attack on the cave would have any hope of success.
The fight for the Pocket was turning into a siege, but the 1st Marine Division believed they could break through enemy opposition. Rupertus ordered continued battalion and regimental assaults believing they would soon bring victory.
When the 321st’s eastward probes brought them within grasp of sealing off the Pocket from the north, they deployed two battalions to complete the encirclement. This assault would absorb the 321st Infantry’s full attention until September 26, while the 5th Marines were fighting in northern Peleliu. The 7th Marines continued to pressure the Pocket from the south. When the 321st broke through on the 26th, their mission was expanded to assault the Pocket from the north.
The 321st broke through in the north and cleared the sporadically defended Kamilianlul Ridge. Their attack along adjacent ridges allowed for the Allied forces’ consolidation on the north side of the Pocket—now 400 yards wide. On September 29, the 7th Marines were ordered to relieve the Army units in the northern sector.
Now that the 2/7 and 3/7 Marines were on static guard duty, hundreds of non-infantry were stripped from combat positions and put into support units. These “infantillery” units were assigned to hold the earlier held sectors. They faced the karst plateau between the Pocket and West Road.
On the 30th, with the 7th Marines’ flexibility restored, they moved south and secured Boyd and Walt’s Ridge. They controlled the East Road, but enemy defenders still harassed them from caves on the west side.
On October 3, the 7th Marines organized a four-battalion attack. This plan called for the 1/7 and 3/7 to attack Boyd’s Ridge from the north, while the 2/7 would attack Walt’s Ridge from the south. The 3/5 would make a diversionary southern attack into Horseshoe Canyon and Five Sisters to its west.
This regimental attack committed four battalions (closer to company strength) against the heights in the southern edge of the Pocket. The assault succeeded, but with heavy casualties. Four of the Five Sisters were scaled but were untenable and had to be abandoned. The next day, the 7th Marines made another attack to seize—then give up positions on Five Sisters.
During this fight, the 3/7 Marines’ push led to a rapid advance that gained them Hill 120. They hoped this would provide a jump-off point for the next day’s operation against the ridge to the west. But Hill 120, as with so many others in the Pocket, came under enemy crossfire, making it completely untenable.
The 3/7 withdrew and suffered heavy casualties. Among these was Captain “Jamo” Shanley, who commanded Company L. When several of his men fell wounded, Captain Shanley dashed forward under heavy fire to rescue two men, bringing them behind a tank. When he returned to help another wounded Marine, a mortar round exploded behind him—killing him instantly. His XO was shot by a Japanese sniper when he ran up to help, but collapsed on top of Shanley with a bullet in his brain.
Captain Shanley was awarded a gold star for the Navy Cross he earned in Operation Backhander at Cape Gloucester on New Britain, where he led his company in the seizure of Hill 660 in the Borgen Bay area.
The 7th Marines had been in the savage Umurbrogol Pocket struggle for two weeks. Under the advice of General Geiger, Rupertus relieved them but was still determined to have his Marines secure the Pocket and turned to his only remaining regiment. Colonel Harris moved in with his 5th Marines. He planned to attack from the north and chip off one ridge at a time.
Subduing the Pocket
On September 30, Peleliu aerial reconnaissance convinced Allied planners that siege tactics were required to clear positions in the Pocket. Colonel Harris believed in being lavish with ammunition and stingy with Marine lives. Harris would use all available fire support before ordering advances.
The 2/5 Marines were in position on October 5, but only reconnoitered positions where heavier firepower could come into play. Bulldozers prepared paths on the north end of the box canyons for tanks and LVT flamethrowers to operate. Light artillery batteries were placed along the West Road to fire point-blank into cliffs at the north end of the Pocket.
Cliffs considered “troublesome” were obliterated by direct fire. The rubble created a ramp for tanks to climb into better firing positions. Light mortars were used to strip vegetation from areas with suspected enemy caves. Planes loaded with napalm-filled belly tanks were also used to bomb enemy targets selected by the 5th Marines as their key objective.
While the 2/5 Marines picked off enemy firing positions in the north, on October 7, the 3/5 assaulted Horseshoe Ridge with tanks. This time the miss
ion wasn’t to seize and hold but to destroy all targets on the faces of Five Sisters and the lower western face of Hill 100.
When all the ammunition was used, tanks withdrew to rearm and then returned accompanied by flame-throwing LVTs and small infantry fire teams. This tactic killed many cave-dwelling Japanese, along with finally silencing their heavy weapons. Before this, single enemy artillery pieces firing from Horseshoe Ridge had harassed the airfield. After the October 7 assaults, no further enemy attacks occurred.
For six more days, the 5th Marines provided all available support to small incremental advances from the north. Light mortars were used to clear vegetation and routes of advance. Both tanks and artillery were used at point-blank range, firing into suspected caves or rough coral areas.
Napalm aerial bombardments cleared vegetation and drove the Japanese defenders farther back into their caves. All advances were limited and aimed at seizing new firing positions. Small platoons and squads made these advances. After Hill 140 was taken, they had a firing site for a 75mm howitzer. The howitzer was wrestled in, disassembled, reassembled, sandbagged, and then fired from position. The 75mm fired into the mouth of a huge cave at the base of the next ridge from where enemy fire had come from for days.
Sandbagging the 75mm howitzer posed several problems. The only available loose sand or dirt had to be carried in from the beach or came from occasional debris slides. The use of sandbags in forward infantry positions increased, and this technique was later widely used when the 81st Infantry Division took over Pocket operations.
Securing the Eastern Ridges