Volumes are written on the Lafayette Escadrille, a French fighter unit composed largely of American volunteers.
There is a lot of valuable sources, books and movies telling the story of the Escadrille organized by Dr. Edmund L. Gros, director of the American Ambulance Service, and Norman Prince, an American expatriate already flying for France. For starters, a page on acepilots.com is highly recommended. Here today, just some images.
To be continued