The De Havilland DH-4 is a British biplane designed by Geoffrey de Havilland in the early 1920s. It was primarily used as a military aircraft during World War I and later adapted for civilian purposes. The DH-4 was known for its reliability and versatility, serving in various roles such as reconnaissance, bombing, and transport. Equipped with a powerful engine, the DH-4 could reach speeds of around 120 mph. Its design featured a distinctive two-wing structure, which provided stability and lift. The aircraft played a significant role in the evolution of aviation, influencing future aircraft designs and paving the way for modern flight.