During U.S. naval exercises in the 1930s, carrier aircraft twice successfully “attacked” Pearl Harbor. After taking notice, the Imperial Japanese Navy would repeat the formula on 7 December 1941.; the familiar sound of aircraft had caught their attention, but something was different this time.
Down at Pearl Harbor, the weather was nicer. The rain had stopped and the clouds were thinning. The majority of the Pearl Harbor–based Pacific Fleet was at anchor along or near Battleship Row, in dry dock receiving maintenance, or at the submarine base. It was dawn, and only a skeleton crew for each ship was on call. Most sailors still were in their racks, many sleeping off hangovers; attending religious services; or eating breakfast.