Pearl harbour is located in Hawaii and was seen as one of the most surprising attacks in history by imperial Japan. It was the location of the American pacific fleet. At that time America had no active role in world war 2.
Fearing an American involvement in japanese plans of expansion in the far east. This was a first strike blow against the Americans.
Japaness imperial navy had sufficient intelligence and therefore the attack took place in the early hours of the 7th of December 1941. Japanese force had over 350 planes. It had used fighters for aerial threats and dive bombers for ships and installations.
The pacific suffered heavy casualties. All eight U.S. Navy battleships were damaged, with four sunk. All but the one ship were later raised, and six were returned to service and went on to fight in the war. The Japanese also sank or damaged three cruisers, three destroyers , an anti-aircraft training ship,and one minelayer. One hundred eighty-eight U.S. aircraft were destroyed; 2,403 Americans were killed and 1,178 others were wounded.
The following day,America had woken up to a tragedy and declared war on Japan.