had been located and the word flashed back to First Army headquarters. The element of surprise, vital to the German plan of a coup de main at the Meuse, was gone. American forces from the 30th Infantry Division were racing in on Peiper from the north, and the 82d Airborne Division was moving with all possible speed to the threatened area.
It is doubtful that Peiper realized how the American net was being spread for a cast from the north, but he had experienced enough reverses on 18 December to feel the stiffening of opposition in his path. Radio contact between Peiper and the higher German headquarters had broken down, the armored sending apparatus failing to carry over the Ardennes terrain, and the Sixth Panzer Army was forced to follow Peiper's progress through intercepted American radio messages. Peiper, on the other hand, had little or no information as to what was happening behind him and where the following kampfgruppen of his own division were located. A Luftwaffe ultrahigh-frequency radio set was rushed to Peiper by liaison officer late this day, but its possession did no alter the relative independence and isolation of Peiper's command.
Sometime during the night of 18-19 December the radio link with the headquarters of the 1st Panzer Division was restored. By this means Peiper may have learned what he already must have suspected, that the 30th Infantry Division was on the move south from the American Ninth Army sector. German reconnaissance and intelligence agencies opposite the U.S. Ninth Army had been alert from the first hours of the counteroffensive for any sign that troops were being stripped from the Roer front for intervention in the south. The first two divisions to leave the Ninth Army area, the 30th Infantry and 7th Armored, actually were in reserve and out of contact, but when the two started moving on 17 December the word was flashed back to OB WEST almost at once. Again American radio security had failed.
During the last days before the great offensive which would send the German armored spearheads plunging west, Hitler belatedly set about replicating the winning combination of rapid and deep armored penetration, paratroop attacks in the enemy rear, and infiltration by disguised ground troops which had functioned so effectively in the western campaign of 1940 and the Greek campaign of 1941. To flesh out this combination, a special operation named Greif (or Condor) was hurriedly organized as an adjunct to the armored operation assigned the 1st SS Panzer Division. 
The plans for the ground phase of Greif consisted of three parts: the seizure intact of at least two bridges across the Meuse by disguised raiding parties, the prompt reinforcement of any such coup de main by an armored commando formation; and an organized attempt to create confusion in the Allied rear areas through sabotage carried out by jeep parties clad in American uniforms. Later it would be rumored that a feature of
 The origins of this scheme are described by Manteuffel in Frieden and Richardson, eds,, The Fatal Decisions, pp. 272-74. See also B. H. Liddell Hart, The Other Side of the Hill (London: Cassell and Company, Ltd., 1951)