After World War II began in Europe in 1939, President Franklin D. Roosevelt announced the neutrality of the United States. Canada declared war on Germany almost at once. As part of the British Commonwealth of Nations, it entered the war on Sept. 10, 1939, one week after Great Britain did.
The majority of people in the United States thought that their country should stay out of World War II. Yet most Americans hoped for an Allied victory. Roosevelt and other interventionists urged all aid "short of war" to nations fighting the Axis. They argued that an Axis victory would endanger democracies everywhere. Isolationists, on the other hand, opposed U.S. aid to warring nations. They accused Roosevelt of steering the nation into a war it was not prepared to fight.
All the countries in North and South America eventually declared war on the Axis. But only Brazil, Canada, Mexico, and the United States sent troops. The United States played a key role in the final Allied victory.
Contributor: James L. Stokesbury, Ph.D., Prof. of History, Acadia Univ.; author, Navy and Empire and A Short History of Air Power.