Humiliated by Sheridan, Warren resigned his commission as major general of volunteers in protest on May 27, 1865, reverting to his permanent rank as major in the Corps of Engineers.
Ydmyget af Sheridan trak Warren sig tilbage som generalmajor i den frivillige hær i protest den 27. maj 1865 og vendte tilbage til sin permanente rang som major i ingeniørkorpset.