Editing George Henry Thomas (section)

===Perryville, Stones River, Chickamauga, and Chattanooga===
[[File:Chickamauga Sep20 3.png|thumb|Defense of Horseshoe Ridge and Union retreat at the [[Battle of Chickamauga]], afternoon and evening of September 20, 1863]]
Thomas resumed service under [[Don Carlos Buell]]. During Confederate General [[Braxton Bragg]]'s invasion of Kentucky in the fall of 1862, the Union high command became nervous about Buell's cautious tendencies and offered command of the Army of the Ohio to Thomas, who refused, as Buell's plans were too far advanced. Thomas served as Buell's second-in-command at the [[Battle of Perryville]], but his wing of the army did not hear the fighting engaged in by the other flank. Although tactically inconclusive, the battle halted Bragg's invasion of Kentucky as he voluntarily withdrew to Tennessee. Again frustrated with Buell's ineffective pursuit of Bragg, the government replaced him with Maj. Gen. [[William Rosecrans]]. Thomas wrote on October 30, 1862, a letter of protest to Secretary Stanton, because Rosecrans had been junior to him, but Stanton wrote back on November 15, telling him that this was not the case (Rosecrans had in fact been his junior, but his commission as major general had been backdated to make him senior to Thomas) and reminding him of his earlier refusal to accept command; Thomas demurred and withdrew his protest.<ref>Broadwater, p. 88-91</ref>

[[File:Thomas's Bivouac at Chickamauga.jpg|thumb|left|Thomas at his bivouac at Chickamauga]]
Fighting under Rosecrans, commanding the [[Stones River Union order of battle|"Center"]] wing of the newly renamed [[Army of the Cumberland]], Thomas gave an impressive performance at the [[Battle of Stones River]], holding the center of the retreating Union line and once again preventing a victory by Bragg. He was in charge of the most important part of the maneuvering from [[Decherd, Tennessee|Decherd]] to [[Chattanooga, Tennessee|Chattanooga]] during the [[Tullahoma Campaign]] (June 22 – July 3, 1863) and the crossing of the [[Tennessee River]]. At the [[Battle of Chickamauga]] on September 19, 1863, now commanding the [[XIV Corps (ACW)|XIV Corps]], he once again held a desperate position against Bragg's onslaught while the Union line on his right collapsed. Thomas rallied broken and scattered units together on Horseshoe Ridge to prevent a significant Union defeat from becoming a hopeless rout.  Future president [[James Garfield]], a field officer for the Army of the Cumberland, visited Thomas during the battle, carrying orders from Rosecrans to retreat; when Thomas said he would have to stay behind to ensure the Army's safety, Garfield told Rosecrans that Thomas was "standing like a rock." After the battle he became widely known by the nickname "The Rock of Chickamauga", representing his determination to hold a vital position against strong odds.<ref>Broadwater, p. 136.</ref>

[[File:Chattanooga Campaign Battles November 24-25.pdf|thumb|[[Chattanooga Campaign|Battles for Chattanooga]], November 24–25, 1863]]
Thomas succeeded Rosecrans in command of the [[Army of the Cumberland]] shortly before the [[Chattanooga Campaign|Battles for Chattanooga]] (November 23–25, 1863), a stunning Union victory that was highlighted by Thomas's troops taking Lookout Mountain on the right and then storming the Confederate line on [[Battle of Missionary Ridge|Missionary Ridge]], the next day. When the Army of the Cumberland advanced further than ordered, General Grant, on Orchard Knob asked Thomas, "Who ordered the advance?" Thomas replied, "I don't know. I did not."