Shortly after the Battle of Richmond on August 29, 1862, David Waller Chenault, a Confederate sympathizer from Madison County, came to Richmond to raise a Confederate regiment. On September 10, 1862, Chenault was commissioned as a colonel and given command of the regiment, dubbed the 11th Kentucky Cavalry. McCreary joined the regiment and was commissioned as a major, the only one in the unit. The 11th Kentucky Cavalry was pressed into immediate service, conducting reconnaissance and fighting bushwhackers. Just three months after its muster, they helped the Confederate Army secure a victory at the Battle of Hartsville. In 1863, the unit joined John Hunt Morgan for his raid into Ohio. Colonel Chenault was killed as the Confederates tried to capture the Green River Bridge at the July 4, 1863, Battle of Tebbs Bend. McCreary assumed command of the unit after Chenault's death. Following the battle, he was promoted to the rank of lieutenant colonel on the recommendation of John C. Breckinridge.