While the United States' armed forces were still years away from entering the Great War in Europe, thousands of naturalized Americans of British and Canadian birth quietly crossed into Canada to answer the Imperial call to arms.

Over 45,000 men and women born in the United States also volunteered to wear the uniform of the Canadian Expeditionary Force and serve His Majesty, King George V. By far the most intriguing groups joining the CEF were the hundreds of ex-servicemen from the United States Army, Navy, and Marine Corps. They provided a cadre of experienced officers and men that had few equals in the force.

This book documents the formation of the American Legion of the Canadian Expeditionary Force, offering a full examination of the political, diplomatic, and constitutional impact of its existence.

A large section is devoted to the issue of recruitment, describing how volunteers were enticed to join, how laws prohibiting American citizens from signing up to serve in the war were circumvented, and the means used by recruiters to meet their quotas. It also documents the heroism and sacrifice of the account of the US citizens who left their homes and families to join the American Legion in order to fight another country's war.