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The Marianas Operation of 1944 marked America's most decisive Pacific campaign, breaching Japan's inner defense perimeter and positioning B-29 bombers within striking distance of the Japanese homeland for the first time. This comprehensive analysis examines the strategic significance, major battles, commanders, units, and weapons that shaped this pivotal moment in World War II.
The Marianas Operation of 1944 marked America's most decisive Pacific campaign, breaching Japan's inner defense perimeter and positioning B-29 bombers within striking distance of the Japanese homeland for the first time. This comprehensive analysis examines the strategic significance, major battles, commanders, units, and weapons that shaped this pivotal moment in World War II.
The distance from Saipan and Tinian to Japan, at roughly 1,400 miles, was well within the 1,500 mile maximum radial range of America's newest heavy bomber, the B-29 Superfortress. The capture of Saipan pierced the Japanese inner defense perimeter, and forced the Japanese government to inform its citizens for the first time that the war was not going well.
The campaign consisted of Operation Forager, which captured the Mariana Islands, and Operation Stalemate, which captured Palau. The operation represented the largest amphibious assault in the Pacific to that date, involving unprecedented naval and air power coordination.
Key Strategic Objectives:
|
Position |
Commander |
Service |
|
Commander-in-Chief, Pacific Ocean Areas |
Admiral Chester W. Nimitz |
U.S. Navy |
|
Fifth Fleet Commander |
Admiral Raymond A. Spruance |
U.S. Navy |
|
Joint Expeditionary Force (TF-51) |
Vice Admiral Richmond K. Turner |
U.S. Navy |
|
Fast Carrier Task Force (TF-58) |
Vice Admiral Marc A. Mitscher |
U.S. Navy |
|
Expeditionary Troops |
Lieutenant General Holland M. Smith |
U.S. Marine Corps |
Admiral Jisaburō Ozawa commanded the Mobile Fleet from his newly commissioned flagship, Taihō. A new commander-in-chief of the Combined Fleet, Admiral Soemu Toyoda, was appointed, and he finalized the Japanese plans known as Plan A-Go or Operation A-Go.
Admiral Raymond A. Spruance's 500-ship fleet, carrying about 125,000 Marines and Sailors steamed 1,000 miles from the Western Marshall Islands to the South Mariana Islands.
Task Force 58 - Fast Carrier Task Force:
The battle was the largest carrier-to-carrier engagement in history, involving 24 aircraft carriers, deploying roughly 1,350 carrier-based aircraft.
Japanese Fleet Organization:
The initial invasion triggered the Battle of the Philippine Sea, which effectively destroyed Japanese carrier-based airpower on June 15, 1944.
American Forces:
The Japanese fought ferociously, holding out in caves and other fortified positions, especially around Mount Tapotchau, the island's highest point.
Battle Statistics:
The aerial part of the battle was nicknamed the Great Marianas Turkey Shoot by American aviators for the severely disproportional loss ratio inflicted upon Japanese aircraft by American pilots and anti-aircraft gunners.
"Why, hell, it was just like an old-time turkey shoot down home!" - USS Lexington pilot during debriefing
American Aircraft Advantages:
|
Metric |
American Forces |
Japanese Forces |
|
Aircraft Lost (Day 1) |
29 planes |
Some 300 aircraft |
|
Aircraft Lost (Day 2) |
Additional losses |
Additional 65 Japanese planes |
|
Carriers Sunk |
0 |
Shokaku and Taiho (Day 1), Hiyo (Day 2) |
|
Total Aircraft Lost |
Nearly 600 aircraft (200 land-based, 400 carrier-based) |
|
The invasion of Saipan was scheduled for 15 June 1944, with landings on Guam tentatively set for just three days later, but the Battle of the Philippine Sea and stubborn resistance by the unexpectedly large Japanese garrison on Saipan led to the postponement until July 21, 1944.
American Forces:
Japanese Forces:
Guam was ultimately captured on August 10, 1944, with the U.S. suffering around 1,400 fatalities and 5,600 wounded, while Japanese casualties were significantly higher, estimated at about 10,000.
Major General Clifton B. Cates's 4th Marine Division landed on Tinian on 24 July 1944, supported by naval bombardment and the guns of the XXIV Corps Artillery, firing across the strait from Saipan.
Tactical Innovation: Instead of landing in the southwest, they landed on the northwest coast, where there were two small beaches that were lightly defended.
Three battleships, 3 cruisers, and 24 destroyers were used to provide naval gunfire. The 155mm "Long Tom" guns of Gen Harper's artillery ranged the length and width of the island, and 105mm howitzers pummeled the northern portion. Daily air strikes and a new aerial weapon called "napalm" were also used to destroy enemy positions.
Battle Statistics:
Gen H.M. Smith called Tinian the "perfect amphibious operation."
F6F Hellcat Specifications:
Japanese planes were highly maneuverable and had a longer range than U.S. planes, but they were inferior in several respects, particularly in their inadequate armour protection and lack of self-sealing fuel tanks.
Fire Support Systems:
By October 1943, U.S. military planners decided that the capture of the Mariana Islands by the summer of 1944 was of the utmost strategic importance. The campaign achieved all primary objectives:
The Marianas Operation fundamentally altered the Pacific War's trajectory by:
