Photograph of personnel inspecting O/400 airplane
Handley Page O/400 being inspected by military personnel. The Handley Page was a British-made bomber used by the US in WWI. War surplus O/400s were given to the Post Office Department after the conclusion of the war. They were never used in any quantity, however parts were used in the modifications of the POD's DH-4s.
Courtesy of the National Air and Space Museum