When Bragg advanced into Kentucky in the summer of 1862 Chalmers' command was a part of his force, performing its duties with courage and zeal. In the Battle of Murfreesboro he and his men again rendered brilliant service. In April, 1863, at the request of John C. Pemberton, General Chalmers was transferred to the Department of Mississippi and East Louisiana and placed in command of the Fifth Military District. The district consisted of the top two tiers of counties in Mississippi. In 1864 he was assigned to the command of cavalry brigades of Jeffrey Forrest and McCulloch, forming the first division of Forrest's Cavalry Corps. This cavalry division was subsequently enlarged by the addition of Rucker's Brigade.