Like the bloody World War II island campaigns before it, Peleliu was a fight to capture an airstrip on a speck of coral in the western Pacific. And, as with previous island battles, the Americans would prevail, but at a higher cost than anticipated, against the determined resistance of the Japanse forces.
By the summer of 1944 victories in the Southwest and Central Pacific had brought the war even closer to Japan, with American bombers now able to strike at the Japanese homeland itself. But there was disagreement by the U.S. Joint Chiefs over two proposed strategies to crush the Japanese Empire. One strategy proposed by General Douglas MacArthur called for the recapture of the Philippines, followed by the capture of Okinawa then Formosa for an attack at the Chinese mainland. From there, the eventual invasion of Japan would come. Admiral Chester Nimitz, on the other hand, favored a more direct strategy of bypassing the Philippines, but seizing Okinawa and Formosa as staging areas for the future invasion of Japan's southernmost islands.
As for Peleliu, both commanders' strategies included the invasion of this island, but for different reasons, and the 1st Marine Division had already been chosen to make the assault. To settle this dispute, President Franklin Roosevelt traveled to Pearl Harbor to meet personally with both commanders and hear their respective arguments. After a review of both positions, MacArthur's strategy was chosen. However, before MacArthur could retake the Philippines, the Palau Islands - Peleliu specifically, would have to be neutralized to protect his right flank. What followed would be a ferocious battle lasting more than two months and costing over 12,000 lives.
Source: U.S. Navy web site
see also USS Peleliu