The S.E.5a was a British fighter aircraft used during World War I. Developed by Sopwith Aviation, it first flew in 1916 and became one of the most successful fighters of the war. The aircraft was known for its speed, maneuverability, and firepower, featuring a powerful Vickers machine gun and a robust design. With a top speed of around 138 mph, the S.E.5a played a crucial role in gaining air superiority for the Royal Flying Corps. Its design included a streamlined fuselage and a large wingspan, which contributed to its stability in flight. The S.E.5a was widely used until the end of the war in 1918.