Battle of Hürtgen Forest

The Battle of Hürtgen Forest was a series of battles fought from 19 September to 16 December 1944, between American and German forces on the Western Front during World War II, in the Hürtgen Forest, a 140 km2 area about 5 km 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. commanders' initial goal was to pin down German forces in the area to keep them from reinforcing the front lines farther north in the Battle of Aachen, where the US forces were fighting against the Siegfried Line network of fortified industrial towns and villages speckled with pillboxes, tank traps, and minefields.

Source: Wikipedia