In that fighting the assault battalions had captured much of the crest required to deny the enemy observation and effective fire on the airfield and logistic areas. Light aircraft had begun operating on D plus 5 from Peleliu’s scarred, and still-under-repair airfield. With Purple Beach in American control, the division’s logistical life-line was assured. Although the Japanese still had some observation over the now operating airfield and rear areas, their reduced capability was to harass rather than to threaten.
Department of Defense Photo (USMC) 95661
At a conference held in the 1st Marine Division command post, Col Harold D. “Bucky” Harris, 5th Marines commander, center, explains to MajGen Roy S. Geiger, Commanding General, III Amphibious Corps, left, and MajGen William H. Rupertus, commander of the division, his plan of operations in northern Peleliu.
Furthermore, the Marine front lines in the Umurbrogol had by now reached close to what proved to be the final Japanese defensive positions. Intelligence then available didn’t tell that, but the terrain and situation suggested that the assault requirements had been met, and that in the Umurbrogol it was time for siege tactics. The Japanese defenders also learned that when aerial observers were overhead, they were no longer free to run their weapons out of their caves and fire barrages toward the beach or toward the airfield. When they tried to get off more than a round or two, they could count on quick counter-battery, or a much-dreaded aerial attack from carrier-based planes, or—after 24 September—from Marine attack planes operating from the field on Peleliu.
[Sidebar ([page 20]):]
A Paucity of Reserves
Planning for the seizure of the southern Palaus (Angaur and Peleliu-Ngesebus) had been the responsibility of III Amphibious Corps (Major General Roy S. Geiger). But General Geiger and his staff had been fully occupied during the critical planning weeks, up to and including the capture of Guam, from 21 July to 10 August. The Guam operation ended more than a month later than originally contemplated. Meanwhile, someone else had to fill the corps planning function for the Palau undertaking. A temporary headquarters, X-Ray Corps, under Major General Julian C. Smith was established. The two major tactical tasks of the southern Palau operation were assigned to the Army 81st Infantry Division (Angaur) and 1st Marine Division (Peleliu-Ngesebus). The 81st Division was also tasked to set aside one RCT as corps reserve.
This partition of division level-planning effort was convenient, but it slipped into a gross imbalance in force allocation which was neither recognized nor corrected as plans progressed toward operations. The 1st Marine Division had nine infantry battalions with which to attack more than 10,000 defending Japanese on Peleliu. Major General Paul J. Mueller’s 81st Infantry Division had six infantry battalions with which to attack 1,500 (earlier reported as 2,500) Japanese defenders on Angaur. Terrain and circumstances on the two objective islands were similarly imbalanced. Peleliu was considerably larger and had far more complex terrain. Its defensive fortifications were obviously far more developed, and it offered fewer predictable landing beaches than Angaur. Only the subsequent rapid shifting of plans and higher-level responsibilities can account for such force allocation imbalance not having been corrected at Corps or Expeditionary Troops level. The effect of all these imbalances was still further magnified between 13 and 17 September. Higher level changes in plans and naval decisions stripped III Corps of all its reserves.