Source:
https://en.wikipedia.org/wiki/Battle_of_H%C3%BCrtgen_Forest
On September 19, 1944 The American forces had entered an area known as Hurtgen forest. The "initial goal was to pin down German forces in the area to keep them from reinforcing the front lines further north in the Battle of Aachen, where the Allies were fighting a trench war between a network of fortified industrial towns and villages speckled with pillboxes, tank traps and minefields". "A secondary objective may have been to outflank the front line. The Americans' initial tactical objectives were to take Schmidt and clear Monschau. In a second phase the Allies wanted to advance to the Rur River as part of Operation Queen". "The Germans fiercely defended the area because it served as a staging area for the 1944 winter offensive Watch on the Rhine (German: Unternehmen: Wacht am Rhein—later known as the Battle of the Bulge), and because the mountains commanded access to the Rur Dam at the head of the Rur Reservoir (Rurstausee). If the floodgates were opened, the resulting surge would flood low-lying areas downstream and temporarily prevent forces from crossing the river. The Allies failed to capture the area after several heavy setbacks and the Germans successfully held the region until they launched their last-ditch offensive into the Ardennes. The Battle of the Bulge gained widespread press and public attention, leaving the battle of Hürtgen Forest largely forgotten".