A Japanese assault force under Admiral Inoue including the carrier Shoho, 4 cruisers and a destroyer had landed troops on Tulagi, then joined the larger strike force under Adm. Takagi which included the fleet carriers Shokaku and Zuikaku in the Coral Sea to attack Port Moresby on Papua.

Meanwhile, US Admiral Fletcher with a task force lead by the carriers Yorktown and Lexington and including Australian crusiers and destroyers under Adm. Crace RN, attempted to intercept.

On the 7th, aircraft from both sides spotted each other and launched the first completely carrier-to-carrier battle (no surface ship-to-ship combat occurred) in history. In air attacks on the first day, the Shoho was lost, and a Japanese night attack was unsuccessful. On the 8th, in air strikes on both sides, the Shokaku was damaged, but the Americans lost the Lexington, a destroyer and an oiler while the Yorktown was damaged. In aircraft, the US lost 33 of 82 aircraft, the Japanese 43 of 69. Thus in tactical terms this was a Japanese victory, however with the loss of so many aircraft and the Shoho, the Port Moresby invasion force was withdrawn. Japan was checked, and was not able to launch air attacks on Australia from a land base so the Coral Sea can be considered an Allied strategic win.

The Coral Sea, off the coast of Papua New Guinea