Harfleur (ärflörˈ) [key], town (1993 est. pop. 9,221), Seine-Maritime dept., N France, at the mouth of the Seine River on the English Channel. It was a flourishing port during the later Middle Ages but declined because of silting in the 16th cent. The siege and capture (1415) of Harfleur by the English in the Hundred Years War is described by Shakespeare in Henry V.