tion, for there seems to have been a twilight zone between air and ground headquarters in which the responsibility had not been sufficiently pinned down." 
On 15 December the Allied air commanders' conference at SHAEF convened to review the big picture. Here the SHAEF G-3 told the assembled airmen that the Roer dam operations had failed to provoke a move by the main enemy armored reserve; as for the VIII Corps front, "nothing to report." Then the A-2 rose to sketch the activities of the Luftwaffe: it had continued the movement westward, closer to the battlefield, which had been noted in recent days, but all this was "defensive" only.
The prelude to the Ardennes counteroffensive of 16 December can only be reckoned as a gross failure by Allied ground and air intelligence. One of the greatest skills in the practice of the military art is the avoidance of the natural tendency to overrate or underestimate the enemy. Here, the enemy capability for reacting other than to direct Allied pressure had been sadly underestimated. Americans and British had looked in a mirror for the enemy and seen there only the reflection of their own intentions.
The German Concentration
Hitler's operation directive of 10 November set z7 November as the date for completion of the huge concentration preliminary to the Ardennes counteroffensive, with a target date two days earlier for the attack by the divisions in the initial thrust. But his commanders in the west, better versed in logistics, recognized from the first that the attack could not be made before the very last of the month. The Allied attacks in the Aachen and Metz sectors made further postponement unavoidable, pinning German divisions to the front long beyond their planned date of relief and bringing others back into the line when refitting had only just begun. Inside the Greater Reich the Replacement Army, charged with creating and training new Volks Grenadier divisions for the offensive, proved Hitler's optimism ill-founded. The task of building new divisions from air force troops, sailors, and the products of Goebbel's raid on the remaining civilian population was immense, the timing necessarily slow. In early December, when Hitler's target date had come and gone, another factor intervened to cause delay. The preliminary movement of armored divisions and vehicular columns had burned up far more fuel than German quartermasters had reckoned. The attack would have to be delayed until the diminished fuel tanks west of the Rhine could be replenished.
The concentration period, therefore, would run until 16 December but even these added days gave all too short a time for such a formidable array of preparations. The original plans called for the movement and assembly of 4 armies, 11 corps, 38 divisions, 9 Volks artillery corps, and 7 Volks Werfer brigades, plus service and support troops. By the beginning of December OKW's inflated order of battle had been reduced to about 3o divisions (the Fifteenth Army now was deleted from the initial attack order, although still envisioned as the subsidiary attack force), but the logistics
 Ibid., p. 681.