In February, 1864, he was put under arrest for falsely representing himself as colonel of the 68th New York Volunteer Infantry Regiment and enriching himself by raising funds from young officers who expected that he could obtain commissions for them in his regiment. He was eventually released and actually appointed colonel of New York's 68th in June, 1864, serving under Brigadier General James B. Steedman in Tennessee and Georgia, he took part in the Battle of Nashville, and toward the end of the war was assigned to the command of the post at Atlanta. Salm-Salm was mustered out of the volunteers on November 30, 1865. On January 13, 1866, President Andrew Johnson nominated him for appointment to the grade of brevet brigadier general, to rank from April 13, 1865 and the U.S. Senate confirmed the appointment on March 12, 1866.Eicher, 2001, p. 756.
