In early 1864, Fesler's regiment was transferred to the new 20th Army Corps, which retained the old corps badge of the 12th. Now as part of the 20th Corps, Fesler and the 27th took part in the Atlanta campaign, fighting at the Battle of Resaca and at the Battle of Kennesaw Mountain. He again commanded the regiment at the Battle of Peachtree Creek on July 20, 1864, when the colonel was wounded. Fesler and the 27th Indiana mustered out in November 1864.