Mariana and Palau Islands campaign
The United States launched Campaign Plan Granite II against Imperial Japanese forces in the Pacific between June and November 1944. This offensive aimed to neutralize Japanese bases in the central Pacific while supporting the Allied drive to retake the Philippines. Overall command rested with Admiral Chester W. Nimitz following the Gilbert and Marshall Islands campaign. The operation sought to provide secure bases for a strategic bombing campaign directly against Japan itself. Planners intended to cut off Japanese supply lines and establish forward operating points for future invasions.
Imperial Japanese Navy's Combined Fleet sortied to attack U.S. Navy forces on June 19 and 20, 1944. The resulting Battle of the Philippine Sea became known as the Great Marianas Turkey Shoot. Japanese naval forces suffered heavy and irreplaceable losses to their carrier-borne and land-based aircraft. This decisive defeat crippled Japanese carrier capabilities for the remainder of the war. United States carrier groups maintained air superiority throughout the engagement while inflicting catastrophic damage on opposing forces.
Operation Wedlock ran prior to landings in Guam and Tinian to mislead Japanese intelligence. Increased radio traffic starting in October 1943 purported a I Alaskan Corps preparing to invade Kurile islands. A joint army-navy radio task force operated out of Adak, Alaska to generate fake transmissions. These signals targeted a fictitious IX Amphibious Force and 9th US Fleet to create confusion. The deception campaign successfully diverted attention away from actual invasion targets in the Mariana Islands.
U.S. forces landed on Saipan in June 1944 followed by Guam and Tinian in July 1944. Heavy fighting secured Saipan by July while Guam and Tinian fell in August 1944. Marine and Army units then attacked Peleliu and Angaur in Palau during September 1944. Both islands were finally secured by November 1944 after intense combat operations. The main Japanese garrison on Koror was bypassed altogether until surrendering in August 1945 with Japan's capitulation.
Allied forces constructed airfields on Saipan and Tinian immediately following their capture. B-29 bombers flew from these bases to conduct strategic bombing missions against the Japanese home islands. These attacks continued until the end of World War II without interruption. The aircraft launched nuclear strikes on Hiroshima and Nagasaki from these forward operating locations. This infrastructure enabled the final phase of the Pacific War to proceed directly toward victory.
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Common questions
When did the United States launch Campaign Plan Granite II against Imperial Japanese forces?
The United States launched Campaign Plan Granite II between June and November 1944. This offensive aimed to neutralize Japanese bases in the central Pacific while supporting the Allied drive to retake the Philippines.
Who commanded the Fifth Fleet during the Mariana and Palau Islands campaign?
Admiral Raymond A. Spruance commanded the Fifth Fleet assembled for this massive undertaking. Vice Admiral Marc Mitscher led Task Force 58 which consisted of fifteen aircraft carriers and seven battleships.
What happened during the Battle of the Philippine Sea on June 19 and 20 1944?
Imperial Japanese Navy's Combined Fleet sortied to attack U.S. Navy forces resulting in heavy and irreplaceable losses to their carrier-borne and land-based aircraft. The resulting defeat crippled Japanese carrier capabilities for the remainder of the war.
How did Operation Wedlock mislead Japanese intelligence prior to landings in Guam and Tinian?
Increased radio traffic starting in October 1943 purported a I Alaskan Corps preparing to invade Kurile islands to create confusion. These signals targeted a fictitious IX Amphibious Force and 9th US Fleet to divert attention away from actual invasion targets in the Mariana Islands.
When were Saipan Guam and Tinian secured by United States forces?
U.S. forces landed on Saipan in June 1944 followed by Guam and Tinian in July 1944. Heavy fighting secured Saipan by July while Guam and Tinian fell in August 1944.