By 20 September, the 81st Division had defeated or cornered all survivors of Angaur’s 1,400 defenders. The 81st’s commander declared Angaur secure. He tasked his 322d RCT to complete the mop-up, and reported to General Geiger that the 321st RCT was available for further operations. The lack of enough troops to begin encircling Umurbrogol was no longer an obstacle.
The other obstacle to reinforcing the division on Peleliu and encircling the Pocket lay in the thinking of General Rupertus, who clung to a belief that his Marines could do it without help from the Army. The III Corps plan tasked the 81st Division to reinforce the Marines in seizing Peleliu and then to relieve the 1st Marine Division for the mop up, but the general continued to exhort his commanders to “hurry up.”
Earlier, General Rupertus and Colonel Puller had shrugged off a suggestion from the 5th Marines’ “Bucky” Harris that they take a look at the Umurbrogol Pocket from the newly available light planes of Marine Observation Squadron 3. Harris’ own aerial reconnaissance, made immediately after those planes arrived on 19 September, had altered his view of the Umurbrogol from sober to grave. It convinced him that attacking the Pocket from the north would be less costly than the originally planned and ordered attempts from south to north. Both Puller and Rupertus responded to Harris that they had their maps.
Once the troops entered the Umurbrogol Mountain, they found sinkholes and difficult terrain much as pictured here. Japanese soldiers in the caves and heights above could fire at will at the Marines, who were like so many “fish in a barrel.”
Department of Defense Photo (USMC) 108432
The prelanding scheme of maneuver was built on the tactical concept that, after capturing the airfield, the 1st Marine Division would push north along a line across the width of the main or western part of the island. Once abreast of the southern edge of Umurbrogol, that concept and maneuver scheme were reflected in a series of four west-to-east phase lines, indicating an expected linear advance, south to north. Clearly, it was expected that the advance along the flatter zones west and east of Umurbrogol would be at approximately the same pace as that along the high-central ground of Peleliu. Such thinking may have been consistent with Rupertus’ prediction of a three-day assault. Developments in Sabol’s sector to the west, and in the 5th Marines’ sector to the east, apparently did not change division-level thinking. Until additional forces became available, such a linear advance may have seemed all that was possible.
Even so, there was no apparent reexamination of the planned south-to-north linear advance, and for days after the Pocket was sealed off at its northernmost extremity, the division commander kept ordering attacks from south to north, generally following the initial landing plan. As had been revealed to “Bucky” Harris in his early aerial reconnaissance of the Umurbrogol Pocket, such attacks would offer little but casualties. Troops, heavily supported, could advance into “the Horseshoe” and into “Death Valley,” but the positions they reached then proved untenable and withdrawal was usual at day’s end.
Some part of this thinking may have well come from the inadequacies of the map in use. The 5th Marines in early October produced a new and more representative sketch map. It located and identified the details within Umurbrogol sufficiently to facilitate maneuver and fire coordination.
That mapping effort, incidentally, led to the misnaming of Honsowetz’ Hill 100, where Captain Everett P. Pope earned his Medal of Honor. The 5th’s mapping team, launched after Harris’ regiment was committed against the Pocket, encountered Lieutenant Colonel Walt, the regimental executive officer, on Hill 100 during their sketching, and so named the hill.