Sheridan's next service was as General Halleck's chief quartermaster in the Corinth campaign. Halleck seems to have thought very well of Sheridan from the first, though apparently rather as a trustworthy organizer and manager, than as such a military son of thunder as he has turned out to be. After a time the nature of the war in those parts occasioned a great demand for cavalry officers, and Sheridan being pitched upon for one, was on May 27, 1862, commissioned colonel of the 2d Michigan Cavalry, and was at once sent into the field to help impede the retreat of the rebels when they should evacuate Corinth. In this and other similar work of that campaign, Sheridan became at once known to the army and to his superiors as a splendid officer, and from that time forward he rose and rose, up to the very last scene of the Virginia campaign, where he wielded the troops that struck the most telling of the final blows against Lee. His first important service was to take part in Elliott's Booneville expedition. In June he had a cavalry combat with the butcher Forrest, and beat him, and was made acting brigadier. In July, having two regiments with him, he was attacked by the rebel Chalmers with six thousand men. Sheridan's position was strong enough, but he saw that he would shortly be surrounded and starved out by mere weight of numbers. So he contrived a neat and effective surprise; risky, it is true; but it is exactly the character of an able commander to take risks at the right time, _and not lose_. Sheridan sent round to the enemy's rear, by a long detour, a force of about ninety troopers, with instructions to fall on at a given time, when he would attack in concert with them. This was done; the bold squad fired so fast from their repeating carbines that the rebels, startled and perplexed, could not estimate on the probable number attacking them, and were thrown into confusion. At this moment, Sheridan charged in front with his whole force, and in his own manner, and Chalmers' men, instantly breaking, fled in total rout, and were pursued twenty miles, leaving the whole road strewn with weapons, accoutrements and baggage thrown away in their flight. General Grant, at this time Sheridan's department commander, reported in strong commendation of Sheridan's conduct in this affair, and asked a brigadier's commission for him, which was accordingly given, dated July 15th, the day of Chalmers' first attack. Sheridan seems to like to be attacked. He is sure of himself and of his men, conscious of his own coolness, view of the field, recognition of the "critical five seconds," and promptness in moving, and he prepares a return stroke apparently quite as gladly as he administers a first assault.