At 05.30 hrs on 16 December, the surprise German offensive began, with 90 minutes of initial volleys from over 1600 guns along a 130-kilometre front. In the more northerly section, the 6th Panzer division attacked the Losheim Gap and Elsenborn Ridge; at the central section, the 5th Panzer division advanced towards Bastogne and St. Vith.
The Americans immediately saw the imminent danger and strategic significance of the situation, and responded instantly. A vital defensive position for the Americans was Bastogne, which formed an important nodal point for traffic in the Belgian Ardennes. The Americans eventually succeeded in defending the besieged Bastogne and repelling the Ardennes offensive.
Heavy losses of soldiers, panzers, fighter aircraft and fuel greatly accelerated the end of the Third Reich.