History: Pearl Harbor Bombing

Over the next several months, pilots trained, equipment was adapted, and intelligence collected. Despite these preparations, the attack plan was not approved by Emperor Hirohito until November 5, after the third of four Imperial Conferences called to consider the matter. Final authorization was not given by the emperor until December 1, after a majority of Japanese leaders advised him the "Hull Note" would "destroy the fruits of the China incident, endanger Manchukuo and undermine Japanese control of Korea." Though by late 1941 many observers believed that hostilities between the U.S. and Japan were imminent, and U.S. Pacific bases and facilities had been placed on alert on multiple occasions, U.S. officials doubted Pearl Harbor would be the first target. They expected the Philippines to be attacked first, due to the threat air bases there, as well as the naval base at Manila, would pose to sea lanes, hence supplies to and from territory to the south, which were Japan's main objective. They also believed (wrongly) that Japan was not capable of mounting more than one major naval operation at a time.
Objectives
The attack had several major aims. First, it intended to destroy important American fleet units, thereby preventing the Pacific Fleet from interfering with Japanese conquest of the Dutch East Indies and Malaya. Second, it was hoped to buy time for Japan to consolidate its position and increase its naval strength before shipbuilding authorized by the 1940 Vinson-Walsh Act erased any chance of victory. Finally, it was meant to deliver a severe blow to American morale, one which would discourage Americans from committing to a war extending into the western Pacific Ocean and Dutch East Indies. To maximize the effect on morale, battleships were chosen as the main targets, since they were the prestige ships of any navy at the time. The overall intention was to enable Japan to conquer Southeast Asia without interference.