In December 1918 Maj. Gen. Mason M. Patrick, Chief of Air Service, American Expeditionary Forces (AEF), directed his newly appointed Assistant Chief of Staff, Col. Edgar S. Gorrell, to prepare a history and final report on U.S. air activities in Europe during World War I. They summarized Air Service activities from the arrival of the first airmen in France in the spring of 1917 until the Armistice on November 11, 1918. Another important document produced under Gorrell's supervision as part of the history of the Air Service, AEF, is a "Tactical History" written by Lt. Col. William C. Sherman and a group of officers working with him in France at the end of the war. The "Final Report" and "Tactical History" published in this volume are products of the historical program of the Air Service, American Expeditionary Forces (AEF). They are part of that monumental compilation of historical narratives and documentary materials that has come to be known as "Gorrell's History."