World War I postcard with a portrait of General John J. Pershing
General John J. Pershing’s portrait on a World War I postcard

At the end of the war, General John J. Pershing—commander of the American Expeditionary Forces (AEF)—wrote a letter of appreciation to the members of the AEF, and that letter begins “My Fellow Soldiers.”
Courtesy Smithsonian’s National Postal Museum