The Eagle Squadrons were three fighter squadrons of the Royal Air Force (RAF) formed with volunteer pilots from the United States during the early days of World War II (circa 1940), prior to America's entry into the war in December 1941. With the United States still neutral, many Americans simply crossed the border and joined the Royal Canadian Air Force (RCAF) to learn to fly and fight. Many early recruits had originally gone to Europe to fight for Finland against the Soviet Union in the Winter War.