The Douglas DC-6 is a piston-powered airliner and transport aircraft built by the Douglas Aircraft Company from 1946 to 1958. Originally intended as a military transport near the end of World War II, it was reworked after the war to compete with the Lockheed Constellation in the long-range transport market. More than 700 were built, and many still fly today in cargo, military, and wildfire control roles. The DC-6 was known as the C-118 Liftmaster in United States Air Force service, and as the R6D in United States Navy service prior to 1962, after which all U.S. Navy variants were also designated as the C-118.