By late 1944 the Allies were poised to smash the Siegfried Line and break into Germany. Supply lines were shorter thanks to the port of Antwerp. Arnhem aside, there had been a long run of victories and there was no intelligence even from ULTRA to suggest a German counter-offensive.**So the major December attack through the mountainous Ardennes by massed Panzers and infantry took the Allies totally by surprise. Fog and low cloud negated the Allies' air supremacy, English-speaking German commandos in captured jeeps created panic and withdrawal of US forces became a near rout with morale all but broken.*For ten days the situation worsened and Antwerp was seriously threatened and 21st Army Group in danger of being cut off.**Clear skies for the Thunderbolts and coherent counter-attacks by rapidly deployed reinforcements turned the tide in the nick of time, so preventing a catastrophic defeat for the Allies.**All this and more is graphically narrated in this fine study of a pivotal battle, that so nearly changed the course of war.