Near the end of January 1863, Colonel Williams resigned his commission and Lieutenant Colonel James died, leaving Major Jordan in command of the 9th. During the Chickamauga campaign during the late summer of 1863, the regiment fought in several skirmishes and captured part of the advance guard of Lt. Gen. James Longstreet's corps. During the Battle of Chickamauga, it guarded the right flank of the Union army, and, after the rout of the Union left wing, continued fighting with Thomas.