A case could be made that the Martin Model 170 Mars four-engine flying boat doesn't even belong in a site devoted to warplanes, since it didn't go operational until after the war. But the giant Mars quickly became a legend in its own time.

Designed as a very-long-range patrol bomber, it was converted to a very successful cargo carrier. When wartime planners wrote about water-based air transport in the postwar world, the Mars was the kind of plane they had in mind. When increasing performance of land-based transport planes made the water-based transport model obsolete, the Mars planes were ultimately sold off. The survivor still serves as a water-bombing fire fighter.