The Ardennes operation was the last significant offensive of the German army and at the same time the largest battle in which Anglo-American troops took part. The offensive spearhead was led by Colonel Joachim Peyper, a decorated veteran of many battles. Over the years of the war, Peiper's regiment turned from a selected military elite into a bunch of hastily drafted youths from all over Europe. The desperation of the Germans pushed them to the senseless extermination of prisoners, called by historians the “Malmedy massacre.”