Dutchman (n.)

late 14c., "member of the German race, person of German birth or ancestry," from Dutch (adj.) + man (n.). From 1590s in narrowed sense of "inhabitant of Holland or the Netherlands," though "Century Dictionary" as late as 1897 reports it "in the U.S. often locally applied to Germans, and sometimes to Scandinavians" (other 19c. sources also include Baltics).

From 1650s in nautical use as "Dutch ship." References to the ghost ship called the Flying Dutchman seem to begin late 18c. (see flying).