The Second Bull Run campaign had been very hard on the III Corps, which sustained heavy losses, including one of its division commanders, and had come close to being driven from the field in panic. On September 4, Heintzelman was relieved from command, being judged as too old and insufficiently aggressive. He spent the remainder of the war commanding the Washington defenses. At war's end in 1865, Heintzelman reverted to the rank of colonel in the regular army. He served on army boards of inquiry and on occupation duty in Texas as part of Reconstruction.