Salomon rejoined the army on September 26, 1862 as colonel of the 9th Wisconsin Volunteer Infantry Regiment and succeeded Frederick, who had been promoted to brigadier general of volunteers, in commanding the regiment. He would lead the 9th Wisconsin Infantry in the First Battle of Newtonia, the Battle of Prairie Grove, the Battle of Helena and the Battle of Jenkins' Ferry. He was mustered out of the volunteers again on December 3, 1864. On January 13, 1866, President Andrew Johnson nominated Salomon for appointment to the grade of brevet brigadier general of volunteers to rank from March 13, 1865, and the United States Senate confirmed the appointment on March 12, 1866.