St. Vith
While the final battles for "St. Vith" were gathering momentum, the Allied high command was moving to meet the crisis. On 20 December, Field Marshal Bernard Law Montgomery – commander of the 21st Army Group – was given command of all troops north of the German advance. This was done to both improve communications and because Montgomery held the ultimate trump card in the battle, an uncommitted reserve, the British XXX Corps. Also on that day, the forces of the U.S. 82nd Airborne Division, under Major General James M. Gavin, made contact with the 7th Armored Division, meeting the condition General Hodges set for command of the "St. Vith" forces shifting to the U.S. XVIII Airborne Corps under Major General Matthew Ridgway. This was done once again to improve communications and set up a secure supply line to the rear. Ridgeway arrived in "Vielsalm" on 22 December, shortly after American forces were driven from "St. Vith". He was aware that Montgomery had already decided to withdraw from the "St. Vith" area. Montgomery had seen the threat of a larger encirclement of American forces, and hoped to gather a reserve west of the Meuse River to finally block the German advance while also eliminating vulnerable salients in the allied lines.