In late September 1863, the Union Twelfth Corps and the 46th were sent to relieve and reinforce the Union army at Chattanooga. In the spring of 1864, the regiment began campaigning with William T. Sherman. Resaca was fought on May 14-15, 1864, and the 46th was engaged on both days, most seriously on May 15, losing 46 men over the course of the fight, including Capt. Ned Witman, Company D, to a foot wound, and Lt. John Knipe, mortally wounded while serving as an aide to his uncle, Brig. Gen. Joseph Knipe.