"Near-complete surprise was achieved by a combination of Allied overconfidence, preoccupation with Allied offensive plans, and poor aerial reconnaissance. The Germans attacked a weakly defended section of the Allied line, taking advantage of heavily overcast weather conditions, which grounded the Allies' overwhelmingly superior air forces. Fierce resistance on the northern shoulder of the offensive around Elsenborn Ridgeand in the south around Bastogne blocked German access to key roads to the northwest and west that they counted on for success. Columns of armor and infantry that were supposed to advance along parallel routes found themselves on the same roads. This and terrain that favored the defenders threw the German advance behind schedule and allowed the Allies to reinforce the thinly placed troops. Improved weather conditions permitted air attacks on German forces and supply lines, which sealed the failure of the offensive. In the wake of the defeat, many experienced German units were left severely depleted of men and equipment, as survivors retreated to the defenses of the Siegfried Line." wiki
Long ago and far away I served with a man named Bill Harris. This was in Turkey in a big NATO headquarters. Harris was a full colonel and a WW2 paratrooper. I was a very young major just back from Vietnam.
Bill was from Missouri, had attended the University of Missouri and had left that institution in the mid-30s when he ran out of money. He joined the pre-WW2 US Army and had reached the rank of sergeant before the Japanese attacked the fleet at Pearl Harbor.
He spent a few months improving the training of National Guard troops as they mobilized for war and then was sent to the Infantry Officer Candidate school at Fort Benning, Georgia. To his surprise he was assigned to the emerging paratroop force at graduation. He served with the 505th Parachute Infantry Regiment of the 82nd Airborne Division throughout the war in Europe.
Bill jumped into; Sicily and Salerno in Italy, Normandy and Holland with the 505th Regiment. He was the only man I ever saw who had four stars embedded in his parachute badge, one for each of his combat jumps. At the end of the Market Garden operation in Holland the 82nd Division was pulled back to a rest and training area outside Paris. There, the division built itself a camp and settled down to wait for spring and an anticipated jump across the Rhine. By that time, Bill Harris was a major and the chief operations staff officer (S-3) of the 505th.
Christmas approached and the division prepared to party. Officers' Class A uniforms were brought over from storage in England so that they would look resplendent for an anticipated grand Christmas gala to be held a few days before the holiday. The front was far to the east and the intelligence people thought the Germans would be inactive for a while, certainly long enough for the 82nd to celebrate. The division's engineers built an amphitheater made of canvas and wood in which to hold the officers' party. The structure had concentric circular platforms on which tables for four were placed at higher and higher levels as one moved away from the center. In the very center of the big tent was a dance floor. The division's band combined forces with part of the Air Corps' Glenn Miller Orchestra to provide music. "Chattanooga Choo Choo" and "American Patrol" sounded through the wintry night for the party. Women and booze were pre-requisites for such an event. Paris was an easy source for the liquor. Army nurses, Red Cross girls and French women from the city were invited and eagerly accepted.