I don't know how old the tune is but one source says the song High Germany (http://www.contemplator.com/folk5/germany.html) (which was printed on a broadside circa 1780) refers to the Seven Years' War (1756-1763). The Seven Years' War was fought between a coalition of Austria, France, Russia, Sweden and Saxony and Prussia (led by Frederick the Great). If your tune has similar dates that may be the Germany meant.

There are a couple of other versions in the database of High Germany. High Germany, The Wars of Germany and Bonnie Lass O' Benachie also refers to "high germany."