But it was the great Civil War which developed Sheridan's talents, as in the case of many other distinguished officers, and made promotion rapid. The resignation of commanders with Southern sympathies and the creation of new regiments secured Sheridan a first lieutenancy in the Fourth Infantry in March, 1861, and a captaincy in the Thirteenth Infantry in the following May. Yet that memorable year in the history of the United States "brought him little employment and no laurels." After various minor services he was commissioned as colonel of the Second Michigan Cavalry on May 25, 1862. He at once engaged with the regiment in Elliot's raid against the railroad, which was destroyed at Booneville. During the month of June he commanded the Second Cavalry Brigade in several skirmishes, and on July 1st gained a brilliant victory at Booneville over a superior cavalry force. His appointment as brigadier-general of volunteers dated from this action. In the autumn of 1862 Sheridan received the command of the Eleventh Division of the Army of the Ohio, under General Buell. Moving out of Louisville with Buell, against Bragg, he took part, on October 8th, in the stoutly contested battle of Perryville, where he manoeuvred his division with conspicuous skill and effect, holding the key of the Northern position, and using the point to its utmost advantage. At the famous battle of Murfreesboro, which was one of the bloodiest and most prolonged of the campaign, Sheridan held the key-point for several hours in the first day's fighting, "displaying superb tactical skill and the greatest gallantry." After repulsing four desperate assaults his ammunition unfortunately gave out. He then ordered a bayonet charge and withdrew his lines from the field; but by his obstinate resistance invaluable time had been gained by his chief, General Rosecrans, to make new dispositions. Sheridan's commission as major-general followed upon these services. From this time little of interest occurred until September 19 and 20, 1863, when Sheridan again distinguished himself at the battle of Chickamauga, rescuing his division from a perilous position. General Thomas was transferred to the command of Rosecrans' besieged army at Chattanooga, and thither General Grant arrived with reinforcements from Vicksburg. Grant was determined to dislodge the Southern commander, Bragg, who was posted on Lookout Mountain and Missionary Ridge. Hooker carried Lookout Mountain and Thomas captured the Ridge on November 25th. In the latter operation Sheridan's division was the first to cross the crest, and it pressed the enemy's rear-guard until long after dark, seizing wagons and artillery. By his successful conduct in the West, Sheridan had now thoroughly established his military reputation.