The Japanese attack on Pearl Harbor was carried out in two major waves of aircraft. The first wave struck shortly before 8 a.m., while the second wave followed at about 8:40 a.m.
The first wave contained torpedo bombers, high-level bombers, dive bombers, and fighters. Its principal targets included American battleships and airfields on Oahu. Torpedo aircraft attacked ships in the shallow harbor, where specially adapted torpedoes could operate.
The second wave concentrated mainly on ships and airfields that remained operational or had escaped serious damage. It included dive bombers, horizontal bombers, and fighters, but no third major wave was launched against the harbor.
Japanese commanders debated whether to send another wave. Admiral Chūichi Nagumo’s force withdrew instead, partly because of concerns about American counterattack, fuel, aircraft losses, and the location of U.S. aircraft carriers, which were not in port. The two-wave structure is therefore different from the number of individual attacks or aircraft sorties.