American D.H.4 "Liberty Planes" in France, probably during the spring of 1918. In all, 4,846 were manufactured in the USA under a grossly mismanaged production programme. The supposedly self-sealing fuel tanks, located between the cockpits, were a fire hazard.

A rebuilt D.H.4 during its first flight on April 14, 1968. “Old 249,” as the aeroplane was known, crashed in 1922 while flying US mail. The remains were recovered and restoration was carried out in time to celebrate the 50th anniversary of the US Air Mail Service. It is currently exhibited at the National Air and Space Museum, Washington.

D.H.4B mailplanes at St Louis for the Detroit News Air Mail Trophy Race, October 6, 1923. The winning D.H. averaged 124-9 m.p.h.

The scene at Maywood Field, Chicago, on May 15, 1926. Lindbergh and Postmaster Green load the first sack of mail to be carried by a contract carrier over CAM-2. Lindbergh was the Robertson Aircraft Corp’s chief pilot and a captain in the Missouri Air National Guard.

Lee Schoenhair’s showpiece D.H.4B at Las Tunas Lake, California, air meet in 1925. Painted maroon, it shone like a piano and the Liberty engine sparkled. It is thought that the aircraft served as a back-up mailplane when Schoenhair joined Pacific Air Transport in 1926.

D.H.4BM AS68212, the personal aircraft of Air Service Chief Maj Gen Mason M. Patrick; St Louis International Air Races, October 1923.

One of the last Government D.H.4Bs in the Air Mail Service was No 372, shown taking off at Sacramento, California, in 1926. No 372 became NC915 in 1927 and, for a time, served the interests of the Richfield Oil Company. It was reduced to ashes during the filming of an air mail epic, circa 1932.

Robertson D.H.4 No 110 at Richards Field, Kansas City, circa November 1926.

Kelly Field D.H.4 No 41, AS23-1325, piloted by Cadet E. B. Schildauer, after its Liberty engine failed.

Test pilot Jack Foote demonstrating a Twin-D.H., November 1919. Efforts to increase the D.H.4’s payload to 800lb led the LWF Company to replace the 400 h.p. Liberty Twelve with twin 200 h.p. Hall Scotts, then 180 h.p. Hissos (shown here). Twenty were built for the Post Office Department, all of which had Liberty Sixes of 240 h.p. Twin D.H.s served on the New York-Cleveland, Cleveland-Chicago and St Louis-Twin Cities Divisions until 1922.

Twin D.H. No 127 being towed from the LWF factory at College Point, Long Island, to the aerodrome.

Twin D.H. no 131 on its back, probably during initial testing.