The role of Americans in the two world wars is well known, but with a glaring exception--one that reveals a little-known aspect of the common history of the United States and Canada. By the time of the American entrance into World War I in April 1917 and World War II in December 1941, tens of thousands of Americans had already fought and died in those conflicts in the uniforms of other nations. Most had quietly traveled over the northern border to join the ground, air and naval forces of the Commonwealth nations, others to France, Poland, China and the other nations and armed forces that played a role in the continuing world conflict of the first half of the century. In preceding their own nation to war, they influenced the course of events in those years and, though threatened with loss of citizenship, were ultimately met with the acceptance of their own government. This book tells the story of who these Americans were, why they took the actions they did, their experiences in war, and the effects of their presence as Americans in foreign forces.