 President Lincoln formally nominated Eaton for the appointment on June 30, 1864, and the U.S. Senate confirmed the appointment on July 2, 1864.Eaton took over the position of commissary general of the Regular Army at the same time due to the death of Brigadier General Joseph P. Taylor on June 29, 1864.On March 8, 1866, President Andrew Johnson nominated Eaton for appointment to the brevet grade of major general to rank from March 13, 1865, and the U.S. Senate confirmed the nomination on May 4, 1866, and re-confirmed it on July 14, 1866, in order to have line officers precede staff officers in rank.