Thirty-two year old John Morrison Oliver was commissioned as a 1st Lieutenant in Company A of the Fourth Michigan Infantry on May 16, 1861. He was promoted to the rank of Captain of Company F on September 25, 1861. On March 15, 1862 he resigned in order to accept a commission as the Colonel of the Fifteenth Michigan Infantry. On January 12, 1865 he was given the rank of Brigadier General in command of the 2nd Brigade, 6th Division for his distinguished service in the attack of Fort McAllister, Georgia on December 13, 1864. On March 13, 1865 John Oliver was brevetted Major General of U.S. Volunteers. John died on March 30, 1872 in Washington D.C. and is buried in Penn Yan, New York.