This was the first aircraft-carrier battle in history, in which the enemy fleets never came closer to one another than 100 km.

The Japanese sent an invasion fleet to seize Port Moresby in Papua New Guinea, from where to bomb Australia. It was turned back when US planes sank a light aircraft carrier. The main fleets had difficulty in locating each other in bad weather: one Japanese aircraft patrol returning after dark mistook the USS Yorktown for their own carrier and attempted to join the 'landing circle' until driven off! The fleets finally made aircraft strikes on each other. One of the two Japanese fleet (heavy) carriers had her flight deck bombed and had to retreat. Both US carriers were hit but not put out of action. Then petrol fumes: a hazard in carriers, exploded in the USS Lexington. Raging fires wrecked her and she had to be sunk. American losses were the greater, but for the first time the Japanese had been turned back and Australia was saved.