Peleliu was the battle that the military wanted forgotten. It was a phyrric victory that bought no tactical value.
Even in my USMC history classes in boot camp, they glossed over Peleliu really quick and went straight on into Guadalcanal, Tarawa, and Iwo Jima.
My understanding is the battle was more a result of MacArthur's ego than anything else. He wanted his flank protected while he went into the Philippines, and while the navy at first agreed, the Marianas campaign made Peleliu inconsequential.
Nimitz eventually was against the invasion, but MacArthur insisted & the marines went ahead with the job.
Consumed many Guadacanal & Pt Glouster vets.