According to Eisenhower the advancement of the 21st Army Group was the most important factor for ending the war. Field marshal Montgomery was given the order to go north into Germany via Belgium and the Netherlands. The 1st US Army of the 12th Army Group had to support them.
The 3rd US Army of the 12th Army Group should join together with the 6th Army Group and clean up the Vosges and the low lands next to the river Rhine. The 6th Army Group consisted of the 7th US Army and the 1čre Armée Française (1st French Army).
At Lorraine and the Alsace was the German 19. Armee (19th Army) under command of general Friedrich Wiese. Parts of this army were moved to the Ruhr in Germany. So there weren't enough soldiers left to make a proper defense line. The first defense line was below the Vosges, but they had to leave it quickly. The second defense line at the top of the Vosges was the same story.
At the end of November there were almost 6 of the 8 divisions destroyed. But the Germans still didn’t get permission from Hitler to withdraw over the river Rhine. Instead of withdrawing, they received the orders to conquer the Alsace again. So they regrouped around the city Colmar to start the counterattack from there.