Edwin P. Hoyt provides in "TO THE MARIANAS: War in the Central Pacific, 1944" an apt and comprehensive summation of the crucial battles in the Central Pacific -- as waged in the Marshalls and Marianas Islands between late January and August 1944.
Both island groups were regarded by Japan (who had occupied them since the end of World War I; the one exception was Guam, which Japan had seized from the U.S. in December 1941) as key in defending the heart of its empire. For the U.S., with its growing naval and air power, it was an imperative to conquer both the Marshalls and the Marianas (along with the retaking of Guam) and use them as bases for bringing the war to Japan itself. Hoyt shows a remarkable knowledge of the series of campaigns -- e.g. Kwajalein, Eniwetok, Saipan, Tinian, and Guam -- which decimated a large part of the Japanese naval and air power in the region til it was little more than a shadow of the colossus which had swept across Southeast Asia and the Pacific in 1941-42. For anyone seeking a general history of the Pacific War, I highly recommend reading this book.