Why did America go to war in 1941?

The reasons many Americans supported isolationism were that they thought they were protected by the Atlantic and Pacific Oceans, international problems were caused by others, they didn't want to risk American lives, they should concentrate on America's economic problems, and the US congress passed some neutrality Acts intended to keep America out of war.

When the German Army invaded Poland, and Britain and France declared war on Germany, the American public were shocked by the Hitler's actions even though most still supported a policy of neutrality. Roosevelt wanted to help France and Britain so sold them weapons on a cash and carry basis (France and Britain had to transport the weapons from America themselves) to make it cheaper. The America First Committee was set up by American isolationists. 'Bundles for Britain' was set up to win support for the Allies, and were opposed by the America First Committee.

He continued to supply arms, and warned Americans that if Germany destroyed the Royal Navy then the USA would be vulnerable. He still promised not to go to war, though, because there was an election and he didn't want to lose votes.

President Roosevelt gave a speech on the four freedoms (of speech, of worship, from want, from fear) to try to persuade isolationists that war was necessary. The Lend-Lease scheme in early 1941 supplied military and other goods to any country whose defence Roosevelt thought was important. The Atlantic charter meant that, after a secret meeting with Winston Churchill, Roosevelt organised more naval patrols in the Atlantic Ocean and protected British convoys as far as Iceland.

In the 1930s, America became concerned over Japan's power in the Far East, and when Japan took over French Indo-China in 1941, Roosevelt froze all Japanese money and assets in the USA. Relations between the two countries deteriorated.

Japan attacked the US base at Pearl Harbour in Hawaii. Japanese planes bombed an American fleet, including 177 planes, 5 battleships, and 5 other vessels lost, as well as serious damage to 8 other vessels, completely unprepared for the attack. 2343 people were killed and 1272 people wounded.

Isolationists were silenced and the next day America declared war on Japan. Britain immediately joined in. On the 11th December, Germany declared war on the USA, so the USA was allied with the Communist Soviet Union who had been attacked by Hitler.