The Battle of Hürtgen Forest (German: Schlacht im Hürtgenwald) was a series of fierce battles fought from 19 September to 16 December 1944 between U.S. and German forces during World War II in the Hürtgen Forest about 50 sq mi (130 km2) east of the Belgian–German border. It was the longest battle on German ground during World War II, and is the longest single battle the U.S. Army has ever fought.The U.S.