In February 1862, Miller was given the command of the 18th Missouri Volunteer Infantry following the removal of W. James Morgan as colonel.[2] In the Battle of Shiloh, Miller commanded the 2nd Brigade in Benjamin Prentiss' division and took part in the fighting in the Hornet's Nest. Despite his courage in battle, he was taken prisoner when the men of the Hornet's Nest defense were captured. He was exchanged and returned to briefly command a brigade in the XVI Corps during the winter of 1863–1864. He resigned in March 1864 but was appointed Brigadier General in the Missouri State Militia in September 1864. He commanded a militia brigade during Price's Raid. On March 13, 1865, he was given a brevet promotion to brigadier general of U.S. volunteers for his service at Shiloh.
↑"Death Roll of a Day". Kansas City Times. St. Louis, Missouri (published February 28, 1896). February 27, 1896. p.2. Retrieved October 8, 2025– via Newspapers.com.