The Mercedes D.III, or F1466 as it was known internally, was a six-cylinder SOHC valvetrain liquid-cooled inline aircraft engine built by Daimler and used on a wide variety of German aircraft during World War I. The initial versions were introduced in 1914 at 120 kW (160 hp), but a series of changes improved this to 130 kW (170 hp) in 1917, and 130 kW (180 hp) by mid-1918. These later models were used on almost all late-war German fighters,