How did the U.S. attempt to avoid involvement in World War II?

After the Great War (World War I) ended in 1918, Americans became deeply disenchanted with international politics and alliance systems. Many Americans came to believe that World War I had been a ghastly mistake; they had poured blood and treasure into a snake pit of ancient rivalries and ethnic hatreds.

From these experiences, Americans learned two things:

  • Avoid any involvement in European or Asian affairs and remain strictly neutral in future wars.
  • Secure between two vast oceans, America didn't need any allies; it needn't rely on any other nation, and it could pursue its interests regardless of what happened anywhere else.

This approach to foreign policy was called isolationism.

To prevent an arms race that could lead to another world war, America signed a number of disarmament treaties to limit the size of naval fleets among Britain, France, Italy, Japan, and the United States. In 1928, this spirit of harmony climaxed with the signing of the Kellog-Briand Treaty, which outlawed war as an instrument of national policy. Also, between 1935 and 1937, Congress passed a series of Neutrality Acts to prevent American bankers and arms makers from making huge profits by providing loans or selling arms to nations at war.

America's neutral stance was coming to an end, however. The day after France and Britain declared war on Germany in September 1939, President Roosevelt addressed the nation. While declaring the United States legally neutral, he said that Americans could not remain neutral in thought: "Even a neutral cannot be asked to close his mind or close his conscience."

France fell to Germany in 1940, and Britain was squarely in Hitler's crosshairs. Americans got nervous. Finally, the Japanese invasion of Pearl Harbor, on December 7, 1941, brought the United States into World War II.