Frank Jack Fletcher
In an attempt to strengthen their defensive positioning for their empire in the South Pacific, Imperial Japanese forces decided to invade and occupy Port Moresby in New Guinea and Tulagi in the southeastern Solomon Islands. The plan to accomplish this, called Operation "MO", involved several major units of Japan's Combined Fleet, including two fleet carriers and a light carrier to provide air cover for the invasion fleets, under the overall command of Shigeyoshi Inoue. The U.S. learned of the Japanese plan through signals intelligence and sent two United States Navy carrier task forces and a joint Australian-American cruiser force, under the overall command of Frank Jack Fletcher, to oppose the Japanese offensive.