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. The narratives written and compiled by Gorrell and his staff were submitted by Patrick to Gen. John J. Pershing, Commander in Chief of the AEF. 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. The "Final Report" was published by the Air Service in an Information Circular in 1921, and by the Army in a multivolume collection of World War I documents in 1948. Although it has been used and cited by a number of historians over the years, it deserves to be better known. The Office of Air Force History, therefore, is republishing it so as to reach a wider circle of persons interested in the Great War and the early history of military aviation. 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. Although published in part in an Air Service Information Circular in 1920, Sherman's "Tactical History" has remained virtually unknown, or at least has not had extensive use. Since it provides excellent information about the conduct of combat operations, it should be of value to persons interested in aerial warfare in the First World War. It has been included, therefore, in this volume with the "Final Report." This is one of a series of volumes of World War I documentation that the Office of Air Force History is planning to publish.