 Complete the following phrase:  By 1 December 1944, the only sector of the front where the Western Allies were not on the offensive was along the Ardennes. In late July 1944, Allied forces in fighting in Normandy were able to break out of the Normandy beachhead in Operation Cobra, forcing a general eastwards retreat of German forces. General Dwight D. Eisenhower, the Supreme Allied Commander on the Western Front, used the opportunity to encircle the German army in Normandy. In an effort to reverse their misfortunes, the Wehrmacht launched Operation Lüttich on 7 August in the vicinity of the town of Mortain. Despite efforts to break through the U.S. 30th Infantry Division to cut off Allied forces in Northern France, by 13 August it was clear that the offensive had failed. Even while battle was raging around Mortain, Allied armies continued the encirclement of the Wehrmacht in Normandy, closing what would be known as the Falaise Pocket on 20 August; the encirclement cost the Germans an estimated 10,000 dead and another 50,000 wounded. Although a much larger number of German soldiers were able to escape eastwards, they were forced to leave behind their heavy weapons and equipment. 