The Battle of the Coral Sea, fought in the waters southwest of the Solomon Islands and eastward from New Guinea, was the first of the Pacific War's six fights between opposing aircraft carrier forces. Though the Japanese could rightly claim a tactical victory on "points", it was an operational and strategic defeat for them, the first major check on the great offensive they had begun five months earlier at Pearl Harbor. The diversion of Japanese resources represented by the Coral Sea battle would also have immense consequences a month later, at the Battle of Midway ("The Battle of the Coral Sea").
The reason that the Battle of the Coral Sea came about was because the Japanese were intent on capturing Port Moresby, New Guinea. Japanese preparations for the occupation of Port Moresby were underway by April. The invasion itself was planned for March, but the appearance of the United States carrier forces in the south-west Pacific had postponed it until May. This attack was called Operation "MO" and if Japanese managed to take Port Moresby they would have a full control over the Coral Sea and they would cut Australia out of the war (Springer).
Some have argued that the Battle of the Coral Sea began on April 28, 1942 when the Japanese began building a seaplane base in Shortland in the Solomons. This would enable four-engine flying boats to begin long-range patrols the next day. However, the actual fighting between the Japanese and American carrier groups lasted from May 4 to May 8 (Springer).
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