Today is the anniversary of one of the most famous events of the battle, the encirclement and survival of the 101st Airborne Division and its attached units at Bastogne. (See maps here and here.)
Bastogne was key. A major road junction, as long as it was in American hands it would cripple the German advance, and if the Nazis took it their advance could have very well rolled all the way to Antwerp.
The Germans needed it, and the Americans had to hold it. Rushed to Bastogne on December 18th, 1944, they were encircled on December 20th. On December 22nd,
What may have been the biggest morale booster came with a reverse twist-the enemy "ultimatum." About noon four Germans under a white flag entered the lines of the 2d Battalion, 327th. The terms of the announcement they carried were simple: "the honorable surrender of the encircled town," this to be accomplished in two hours on threat of "annihilation" by the massed fires of the German artillery. The rest of the story has become legend: how General McAuliffe disdainfully answered "Nuts!"; and how Colonel Harper, commander of the 327th, hard pressed to translate the idiom, compromised on "Go to Hell!" The ultimatum had been signed rather ambiguously by "The German Commander," and none of the German generals then in the Bastogne sector seem to have been anxious to claim authorship.14 Lt. Col. Paul A Danahy, G-2 of the 101st, saw to it that the story was circulated-and appropriately embellished-in the daily periodic report: "The Commanding General's answer was, with a sarcastic air of humorous tolerance, emphatically negative."Completely encircled, cut off from all reinforcements, and limited to what few supplies could be parachuted in, the American troops held on for a week, finally being reached by units of Patton's Third Army on the afternoon of December 26th.
They would remain on the front lines of the battle until late February, 1945. For their stand at Bastogne, the entire division was awarded the Presidential Unit Citation.
More can be found at this website and also here.