Key point: The Japanese losses were irreplaceable.
The Philippine Sea encompasses two million square miles of the western part of the Pacific Ocean. It is bounded by the Philippine Islands on the west, the Mariana Islands on the east, the Caroline Islands to the south, and the Japanese Islands to the north. In the summer of 1944 it was the battleground of two great carrier strike forces. One of these belonged to Japanese Vice Admiral Jisaburo Ozawa. The other belonged to U.S. Admiral Raymond Spruance, and its carriers were under the tactical command of Marc Mitscher. Ozawa had explicit orders to halt the steady advance of the U.S. 5th Fleet, to which Mitscher’s carriers belonged, across the vast Pacific Ocean toward Japan.
Ozawa had the majority of the Imperial Japanese Navy’s fighting fleet under his command at the time, but his force of approximately 90 ships and submarines was still considerably smaller than the U.S. Navy’s 129 ships and submarines. He also commanded 450 carrier-based aircraft that would coordinate with 300 ground-based aircraft in the Marianas.
Ozawa’s strike force steamed east in two groups. The vanguard, comprising three small carriers, four battleships, and other vessels, plowed through the Philippine Sea 100 miles ahead of the main group, which was composed of six large carriers, a battleship, and a wide array of supporting vessels.
Ozawa’s strategy was simple. His vanguard would serve as a decoy to lure the U.S. carrier aircraft while the aircraft from the main group, reinforced with land-based aircraft in the Marianas, inflicted heavy damage in multiple attacks.