This volume deals with the crucial period of the campaign conducted in the Belgian Ardennes and Luxembourg, generally known as the Battle of the Bulge. Although the German planning described herein antedates the opening gun by several weeks, the story of the combat operations begins on 16 December 1944. By 3 January 1945 the German counteroffensive was at an end, and on that date the Allies commenced an attack that would take them across the Rhine and into Germany. The last phase of operations in the Ardennes, therefore, is properly part and parcel of the final Allied offensive in Europe, and so the course of battle beginning on 3 January 1945 is described in another and final volume of this subseries.