The goal of the offensive was to break through the lines of the U.S. Seventh Army and French 1st Army in the Upper Vosges mountains and the Alsatian Plain, and destroy them, as well as the seizure of Strasbourg, which Himmler had promised would be captured by 30 January. This would leave the way open for Operation Dentist (Unternehmen Zahnarzt), a planned major thrust into the rear of the U.S. Third Army which would lead to the destruction of that army.[1]:494