After the successful Tullahoma Campaign, Maj. Gen. William Rosecrans continued the Union offensive, aiming to force Gen. Braxton Bragg’s Confederate army out of Chattanooga. Through a series of skillful marches towards the Confederate-held city, Rosecrans forced Bragg out of Chattanooga and into Georgia. Determined to reoccupy the city, Bragg followed the Federals north, brushing with Rosecrans’ army at Davis’ Cross Roads. While they marched on September 18th, his cavalry and infantry skirmished with Union mounted infantry, who were armed with state-of-the-art Spencer repeating rifles. Fighting began in earnest on the morning of the 19th near Chickamauga Creek. Bragg’s men heavily assaulted Rosecrans’ line, but the Union line held. Fighting resumed the following day. That afternoon, eight fresh brigades from the Army of Northern Virginia under Lieut. Gen. James Longstreet exploited gap in the Federal line, driving one-third of the Rosecrans’ army, including Rosecrans himself, from the field. Only a portion of the Federal army under Maj. Gen. George H. Thomas, staved off disaster by holding Horseshoe Ridge against repeated assaults, allowing the Yankees withdraw after nightfall. For this action, Thomas earned the nickname “the Rock of Chickamauga.” The defeated Union troops retreated to Chattanooga where they remained until late November. Chickamauga is known as one of the bloodiest battles in the Western Theater.