In April 1862, Baird took command of the 27th Brigade, 7th Division in the Army of the Ohio under Maj. Gen. Don Carlos Buell. Baird helped secure the Cumberland Gap in June 1862 under George W. Morgan. He commanded the 3rd Division, Army of Kentucky where his troops fared poorly in the battle of Thompson's Station though Baird was not personally involved. His troops were present at the battle of the Harpeth River before being assimilated into the Army of the Cumberland. Baird's division became the 1st Division of Maj. Gen. George Henry Thomas's XIV Corps. It was in this post that he won fame for his heroic efforts at the Battle of Chickamauga and the Chattanooga Campaign. Baird won a brevet promotion to colonel in Regular Army for Chattanooga. In the Atlanta Campaign, Baird led a brigade charge in the Battle of Jonesborough which earned him the Medal of Honor. He led his division in Maj. Gen. William T. Sherman's March to the Sea and Carolinas Campaign. Baird led his division in the Battle of Bentonville in the latter campaign.