The Airco DH.4 was a British two-seat military reconnaissance aircraft and day bomber designed by Geoffrey de Havilland. It became especially important to the United States, where a version powered by the Liberty engine was manufactured in large numbers. American-built DH.4s were the only American-manufactured aircraft flown in First World War combat by American crews.[1]The DH-4 Liberty Plane at War and in PeaceNational Park Service · nps.gov · Accessed 2026-09-13Open source details
British design and American manufacture
The DH.4 entered combat with the Royal Flying Corps in early 1917. After American entry into the war, an example was sent across the Atlantic for assessment. The American Aircraft Production Board approved manufacture in July, pairing the British airframe with the American Liberty V12 engine.[1]The DH-4 Liberty Plane at War and in PeaceNational Park Service · nps.gov · Accessed 2026-09-13Open source details
The first American-built example emerged in October 1917. Its wooden structure and fabric covering depended on large supplies of suitable timber. The demand for lightweight, strong spruce contributed to the establishment of the United States Army's Spruce Production Division in the Pacific Northwest.[1]The DH-4 Liberty Plane at War and in PeaceNational Park Service · nps.gov · Accessed 2026-09-13Open source details
Combat configuration
The DH.4 carried a pilot and an observer in separate open cockpits. Its American installation combined the Liberty engine with forward-firing armament, flexible guns for the observer and provision for bombs. It was used for both observation and bombing, reflecting the broad duties assigned to two-seat aircraft during the war.[2]De Havilland DH-4National Museum of the United States Air Force · nationalmuseum.af.mil · Accessed 2026-09-13Open source details
The American arrangement placed the main fuel tank between the crew positions. Postwar DH.4B modifications rearranged the cockpit and fuel-tank positions, improving communication between the two crew members and addressing shortcomings of the wartime layout.[2]De Havilland DH-4National Museum of the United States Air Force · nationalmuseum.af.mil · Accessed 2026-09-13Open source details
Operations and later employment
American Liberty-powered DH.4s reached France during 1918 and participated in the Meuse-Argonne campaign. Production continued at a remarkable rate, leaving a substantial inventory available when the fighting ended.[1]The DH-4 Liberty Plane at War and in PeaceNational Park Service · nps.gov · Accessed 2026-09-13Open source details
The aircraft then became an important component of the Army Air Service's peacetime fleet. Observation units continued using it into the 1920s, including the 321st Observation Squadron at Vancouver Barracks. The surviving aircraft exhibited at Pearson Air Museum represents that interwar military service.[1]The DH-4 Liberty Plane at War and in PeaceNational Park Service · nps.gov · Accessed 2026-09-13Open source details