Allied intelligence to give warning of the Ardennes counteroffensive preparations. The failure was general and cannot be attributed to any person or group of persons. The intelligence story on the eve of the Ardennes is not germane in terms of personal opinions or the men who held them. What counts are the views held at the various American headquarters and the gist of enemy information which reached those headquarters. 
In mid-September the Western Allies had felt imminent vicory in their hands. Flushed with their own dazzling successes and heartened by news of the bloody defeats which the Soviet armies were administering to the Germans on the Eastern Front, the Allies saw the Wehrmacht collapsing and the Third Reich tottering to its knees. The pervasive optimism dissipated as the surprisingly revitalized German armies stood their ground in defense of the West Wall, but it never completely disappeared. When the Allied attack began to roll again in late November and early December, some of this earlier optimism reappeared. A 12th Army Group intelligence summary issued on 12 December echoes the prevailing tone: "It is now certain that attrition is steadily sapping the strength of German forces on the Western Front and that the crust of defenses is thinner, more brittle and more vulnerable than it appears on our G-2 maps or to the troops in the line." This optimism, particularly when heightened by reports that the enemy no longer had fuel for tanks and planes, conditioned all estimates of the enemy's plans and capabilities. It may be phrased this way: the enemy can still do something but he can't do much; he lacks the men, the planes, the tanks, the fuel, and the ammunition.
Another aspect of Allied thinking would contribute to the general misconception of German capabilities and intentions. The return of Field Marshal von Rundstedt to command in the west had been marked with much interest by Allied intelligence staffs. Accepted in military circles as one of the best soldiers in the world, Rundstedt's reputation, even among his opponents, rose to new stature as the result of the stubborn German defense in the autumn of 1944. Here, then, was a commander who could be expected to act and react according to the rational and accepted canons of the military art. He would husband his dwindling resources, at an appropriate time he would counterattack in accordance with available means, and ultimately he would fall back to the Rhine for the major defensive battle. Had Rundstedt actually commanded in the west, as the Allies believed, this analysis would have been correct.
(Rundstedt's effort to delimit the scope of the Ardennes counteroffensive in order to achieve a reasonable symbiosis between the means and the end proves the point.)
But Hitler alone commanded. Intuition, not conventional professional judgment, would determine German action. Unaware of the true nature of the German decision-making process in the west, the Allied commanders and staffs awaited an enemy reaction which would be rational and therefore predictable. If the thought ever occurred to an Allied intelligence officer that Germany would
 Pogue, The Supreme Command, pp. 361-72. This is the best treatment of the problem of personal responsibilities for the various Allied intelligence estimates.