1863 map of Battle of Chatanooga on November 23-25, 1863.The Union army retreated to Chattanooga after their defeat at Chickamauga Creek. The Confederates followed and laid siege. General Ulysses S. Grant was appointed commander and immediately removed General William Rosecrans and ordered a doubling of the Union forces in the area. This was a decisive victory for Grant and forced the Rebel army back to Dalton, Georgia.