...rossing the Cumberland Mountains, the Tennessee River, and two mountain ranges beyond. Bragg, seriously alarmed lest Rosecrans should seize the railroad communications behind him, hastily evacuated Chattanooga , but not with the intention of flight, as Rosecrans erroneously believed and reported. When, on September 9, the left of Rosecrans's army marched into Chattanooga without firing a shot, the Union d...