In 1931 Japan had attacked and overrun the Chinese province of Manchuria. Japan ignored American protests, and in the summer of 1937 they launched a full-scale attack on the rest of China. Although this worried the USA and other nations they did not want to go to war about it.

Over the next three years, war broke out in Europe and Japan joined Nazi Germany and Fascist Italy in the Axis Alliance. As well as other sanctions the United States put an embargo on oil. The Japanese hated this.

By the summer of 1941, Japan had decided on war.

The Japanese felt that this would be a good time to conquer British, American, French, Chinese, and Dutch territories in Southeast Asia. They felt that first they had to destroy the US fleet so it could not interfere with their invasion plans. The Japanese thought they would make a surprise attack on the Pacific Fleet while it lay at anchor at Pearl Harbour. With the fleet wiped out the Japanese thought they could secure the Pacific.

The 130 vessels of the U.S. Pacific Fleet were berthed in Pearl Harbour. Seven of the fleet's nine battleships were tied up along "Battleship Row. Naval, Marine and the U.S. Army Air Corps aircraft were all lined up at various places on the island.
At 6:40 a.m., the crew of the destroyer USS Ward spotted the tower of a Japanese midget subs headed for the entrance to Pearl Harbour. The Ward sank the sub with depth charges and gunfire. They then radioed the information to headquarters. Before 7 a.m. the radar station at Opana Point picked up a signal showing a large flight of planes approaching from the north. These were thought to be either aircraft flying in from the carrier Enterprise or an anticipated flight of B-17s from the mainland, so no action was taken.

The first wave of Japanese aircraft arrived over their target areas shortly before 7:55 a.m. Their leader, Commander Mitsuo Fuchida, sent the coded messages "To, To, To" and "Tora, Tora, Tora," telling the fleet that the attack had begun and that surprise had been achieved.

At approximately 8:10, the USS Arizona exploded, hit by a 1,760-pound armour-piercing shell that slammed through her deck and ignited her forward ammunition magazine. In less than nine minutes, she sank with 1,177 of her crew. The USS Oklahoma, hit by several torpedoes, rolled over, trapping more than 400 men inside. The USS California and USS West Virginia sank at their moorings, while the USS Utah, converted to a training ship, capsized with more than 50 of her crew. The USS Maryland, USS Pennsylvania, and USS Tennessee all suffered significant damage. The USS Nevada attempted to run out to sea but took several hits and had to be run aground to avoid sinking and blocking the harbour entrance. While the attack on Pearl Harbour intensified, other military installations on Oahu were hit. Hundreds of planes were destroyed on the ground and hundreds of men killed or wounded.

After a lull, at 8:40 a.m. the second wave of attacking planes arrived destroying the USS Shaw, Sotoyomo, a dry dock, and heavily damaging the Nevada, forcing her aground. The Japanese also attacked Hickam and Kaneohe airfields, causing heavy loss of life and reducing American ability to retaliate.

Army Air Corps pilots managed to take off in a few fighters and may have shot down 12 enemy planes. At 10 a.m. the second wave of attacking planes withdrew to the north, and the assault was over. The Japanese lost 29 planes. They also lost five midget submarines, one of which was captured when it ran aground off Bellows Field.

The attack was a great, but not total, success. Although the U.S. Pacific Fleet was shattered, its aircraft carriers (not in port at the time of the attack) were still afloat and Pearl Harbour was surprisingly intact. The shipyards, fuel storage areas, and submarine base suffered no more than slight damage.

The following day, President Franklin Roosevelt, called December 7 "a date which will live in infamy." American Congress declared war against Japan. Within days, Japan's allies, Germany and Italy, declared war on the United States. The USA began a rapid build up of armaments in support of military campaigns in the Pacific, North Africa, and Europe
The attack on Pearl Harbour had changed the minds of many who had been opposed to becoming involved in the war in Europe. They rallied together determined to defeat Japan and her partners, Germany and Italy.

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