The Mariana and Caroline Islands
Saipan, Tinian, Guam, and Peleliu
Copyright © 2005-6, Henry J. Sage

The Mariana Islands, which include the islands of Guam, Saipan, and Tinian lie about 1200 miles west northwest of Kwajalein and about 1350 miles south of Tokyo. The decision to attack to marry and this was based upon a desire to keep pressure on the Japanese in the Central Pacific and to create air bases from which bombers could attack Japan directly. With the Marshalls as a base from which to operate, the attack on the Marianas was feasible. The leapfrog strategy was beginning to pay off.

The United States had acquired the island of Guam as a result of the Spanish-American war, but the remainder of the Marianas had been in Germany's possession until after the First World War, when they were awarded to Japan. One of Japan's first objectives after the outbreak of World War II was the capture of Guam. The Japanese had constructed to air bases on the island of Saipan. Because the United States forces had been advancing so rapidly through the Central Pacific, the defenses on Saipan were not as far developed as the Japanese had hoped, though the Japanese had substantial troop concentrations totaling about 29,000 throughout the Marianas.

A task force of approximately 800 vessels was assembled to carry soldiers and Marines from bases over 1000 miles away to the Marianas landings. Both Navy and Marine planners that continued to refine the techniques of amphibious warfare, and improvements in supporting equipment and Landing craft had continued apace. The overall commander of the operation was Admiral Raymond A. Spruance, USN, Commander Fifth Fleet. Lieutenant General Holland M. Smith was in command of the entire landing force for the attack on the Marianas.

Coordination of the invasion it was complex, as troops came from as far away as Hawaii. Prior to the invasion, as was done at the previous objectives, naval gunfire and aircraft were used to soften up the defenses of the islands. Saipan was bombed heavily on June 12 and 13, 1944, and naval gunfire operating directly against the shore targets began on the 13th. As had been the case in the past, however, many heavily fortified and well dug in Japanese defensive positions remained intact.

On June 15 and 16th the Second and Fourth Marine Divisions and the 27th Army division landed on Saipan. With a large number of troops in a relatively confined area, confusion ensued on the beaches as units became mixed up, but the Marines were aware of their objectives and advanced resolutely in the face of heavy defensive fire. During the first night ashore the landing force encountered Japanese counterattacks, which were successfully repulsed. On D-Day plus 1 additional troops were landed in the advance continued relentlessly for over three weeks until the island of Saipan was secured. 

Within a few days after the end of the Saipan operation the Second and Fourth Marine Divisions moved in the neighboring island of Tinian, which was taken in a matter of approximately 2 weeks, and by the middle of August the island of Guam was also secured.  The recapture of Guam, a former possession of the United States, was a high point of the Pacific war.

Once the islands were secured a large air base was prepared from the Japanese space that had existed prior to the landing, and B-29 bombers were soon using Saipan as a launch point for raids on the home islands of Japan. On August 6, 1945, the B-29 named the Enola Gay took off from Saipan and dropped the first atomic bomb in history on the Japanese city of Hiroshima.

Peleliu

The island of Peleliu in the Palau Islands lies between the Mariana Islands and the Philippines and was initially considered an important objective in the overall advance through the Western Pacific.  In retrospect it has been suggested that it might have been well to bypass the Palau Islands, but Admiral Nimitz never canceled the operation, and it went forward.

Initial intelligence suggested that Peleliu would be a relatively easy target, but such was not the case.  The terrain on the island consisted of coral ridges in which caves had been dug and reinforced with concrete and other obstacles. Thus the pre-invasion bombardments did little damage to the Japanese defenders. 

The first Marine division landed on September 15, 1944 and the Marines found the going extremely tough. Fighting in extreme heat with temperatures will over 100 degrees, Marines found advancing physically troublesome over the sharp coral, which could even cut through boots. Marines had captured the airfield which was the main objective by September 30, but there were still many Japanese on the island and the fighting continued into November.  The assault on Peleliu cost over 1,000 killed and 5,000 wounded. The job of the Americans was made slightly easier because the Japanese were beefing up defenses in the Philippines and the Ryukus (Okinawa); nevertheless, the fighting on Peleliu was some of the most brutal of the war.