_Possibly one of the best preserved specimens of its kind in the
Pacific this Model 10 120mm dual-purpose antiaircraft and coastal
defense gun is on the western shore of Ngesebus. The gun rests on its
skid plate and was sited in a natural position._]
Such concentrated support enabled the heavily depleted 3d Battalion,
5th Marines, to quickly seize Ngesebus, destroying 463 of Colonel
Nakagawa’s battle-hardened and well-emplaced warriors in 36 hours, at a
cost of 48 American casualties.
Other maneuver elements on Peleliu also were attacking during those 36
hours, but at an intensity adjusted to the limited support consequent
upon General Rupertus’ all-out support of the day’s primary objective.
As 3/5 was clearing Ngesebus, the rest of the 5th Marines was fighting
the Japanese still in northeast Peleliu. After capturing Akarakoro
Point beyond Amiangal Mountain, 2/5 turned south. It swept through the
defenses east of that mountain with demolitions and flamethrowers, then
moved south toward Radar Hill, the eastern stronghold of Hill Row. That
feature was under attack from the south and west by 1/5. After two
days, the two battalions were in command of the scene, at least on the
topside of the hills. Inside there still remained stubborn Japanese
defenders who continued to resist the contest for Radar Hill, as did
the defenders within Amiangal Mountain’s extensive tunnels. All could
be silenced when the cave or tunnel mouths were blasted closed.
[Illustration: UMURBROGOL POCKET]
As these operations were in progress, the 321st at the north end of
Umurbrogol completed seizing Hills 100 and Hill B, then cleared out the
ridge (Kamilianlul Mountain) and road north from there to the area of
5th Marines operations. On 30 September the 321st relieved the 1st and
2d Battalions of the 5th Marines in northern Peleliu. That regiment
reassembled in the Ngardololok area, before it became once more
necessary to commit it to the Umurbrogol Pocket.
_The Umurbrogol Pocket: Peleliu’s Character Distilled_
In a very real sense, the Umurbrogol Pocket typified the worst features
of the post D-Day campaign for Peleliu. It provided the scene of
some of Peleliu’s worst and most costly fighting, and of some of the
campaign’s best and worst tactical judgments. Its terrain was the most
difficult and challenging on the island. Prelanding planning did not
perceive the Pocket for what it was, a complex cave and ridge fortress
suitable to a fanatic and suicidal defense. Plans for the seizure
of the area treated the Pocket’s complex terrain as oversimplified,
time-phased linear objectives to be seized concurrently with the flat
terrain abutting it to the east and west.
The southern slopes (generally called Bloody Nose) dominated the
landing beaches and airfield, over which the Pocket had to be
approached. After those heights were conquered by the heroic and costly
assaults of Puller’s 1st Marines (with Berger’s 2/7 attached), and
after the division had set in artillery which was controlled by aerial
observers overhead, the situation changed radically. The Pocket’s
defenders thereafter retained only the capability to harass and delay
the Americans, to annoy them with intermittent attacks by fire and with
night-time raids. But after D plus 4, Umurbrogol’s defenders could no
longer seriously threaten the division’s mission.
[Illustration: _This sketch shows the floor plan of the largest and
most elaborate tunnel system discovered by Marines on Peleliu. It was
prepared by Japanese naval construction troops and was so elaborate the
Americans thought it might be a phosphate mine._]
Nevertheless, after the critical enemy observation sites were seized,
General Rupertus kept urging “momentum,” as though the seizure of the
Pocket were as urgent as had been seizure of the commanding heights
guarding it from the south. The stubborn character of the terrain, and
its determined defenders, became entwined with the determined character
of the general commanding the 1st Marine Division. This admixture was
sorted out only by time and by the reluctant intercession of General
Geiger. Most of the offensive effort into the Pocket between 21 and 29
September was directed from south to north, into the mouths or up onto
the ridges of the twin box canyons which defined the Pocket. Infantry,
supported by tanks, air, and flame-throwing LVTs could penetrate the
low ground, but generally then found themselves surrounded on three
sides. Japanese positions inside the ridges of the canyons, hidden from
observation and protected in their caves, were quite capable of making
the “captured” low ground untenable. Other attacks, aimed at seizing
the heights of the eastern ridges, while initially successful, in
that small infantry units could scramble up onto the bare ridge tops,
thereafter came under fire from facing parallel ridges and caves. They
were subject to strong night counterattacks from Japanese who left
their caves under cover of darkness.
During 20 September, D plus 5, the 7th Marines had relieved the 1st
Marines along the south and southwest fronts of the Pocket, and on the
21st the 3d and 1st Battalions resumed the attack into the Pocket, from
southwest and south. These attacks achieved limited initial successes
behind heavy fire support and smoke, but succeeded only in advancing to
positions which grew untenable after the supporting fire and smoke was
lifted. Assault troops had to be withdrawn under renewed fire support
to approximately their jump-off positions. There was little to show for
the day’s valiant efforts.
Attacks the next day (22 September) against the west shoulder of
the Pocket, from the West Road, up the western box canyon (Wildcat
Bowl) and toward Higashiyama (Hill 140), all liberally supported with
firepower, again produced early advances, most of which had to be
surrendered at day’s end, as all three attacking groups came under
increasing fire from the Japanese hidden in mutually supporting cave
positions. The 7th Marines had, unbeknown to it, reached within about
100 yards of Colonel Nakagawa’s final command cave position. However,
many supporting ridges, and hilltops, would have to be reduced before a
direct attack upon that cave could have any hope of success.
The fight for Umurbrogol Pocket had devolved into a siege situation,
to be reduced only by siege tactics. But the 1st Marine Division’s
commander continued to cling to his belief that there would be a
“break-thru” against the enemy’s opposition. He insisted that continued
battalion and regimental assaults would bring victory “very shortly.”
When the 321st’s probes eastward near the northern end of the Pocket
brought them within grasp of sealing off that Pocket from the north,
they deployed two battalions (2d and 3d) facing eastward to complete
the encirclement.
[Illustration: