Ex Bontecou Album.  In April 1861, Barnes was stationed at the Army's Fort Vancouver in Washington Territory, the second-ranking officer behind future Union general Edward Ord. On June 4, he was ordered east and departed Fort Vancouver on June 24, 1861.[1] He soon served successively as medical director of the forces under Major General David Hunter, medical director of the Western Department, and medical director of the Department of Kansas. On May 2, 1862, he was ordered to report to the Surgeon General in Washington and upon reporting was assigned to duty as attending surgeon for the city. While on this duty he formed the acquaintance of U.S. Secretary of War Edwin M. Stanton, who quickly gained a highly favorable impression of him.On February 9, 1863, Barnes was appointed a medical inspector with the rank of lieutenant colonel, stationed in Washington. On August 10, 1863, he was further advanced to the position of medical inspector general with the grade of colonel. It was but a few weeks after this advancement that the difficulties between Stanton and Surgeon General William Alexander Hammond culminated in the detachment of the latter from his office. On September 3, 1863, Barnes was by a special order of the War Department "empowered to take charge of the bureau of the Medical Department of the army and to perform the duties of Surgeon General during the absence of that officer."[citation needed] He assumed the office of acting Surgeon General the following day thus beginning one of the longest and most eventful administrations in the history of the office.On August 22, 1864, he was advanced to the position of Surgeon General, with the grade of brigadier general and on March 13, 1865, he received the brevet of major general for faithful and meritorious service during the war. As principal assistant, Barnes brought to his office Major Charles Henry Crane, who continued in the capacity throughout the eighteen years of his term and succeeded to the office upon the retirement of his chief.Lincoln assassinationMain article: Abraham Lincoln AssassinationOn April 14, 1865, at the time of the assassination of United States President Lincoln and the attempted assassination of Secretary of State William H. Seward, Barnes attended the death bed of Lincoln and ministered to the successful restoration of Seward.The morning after Abraham Lincoln's death, three Army Medical Museum pathologists entered the White House to perform an autopsy on Lincoln's body. Overseen by Barnes, the autopsy was conducted by Colonel Joseph Woodward and Major Edward Curtis. The autopsy began at 11 a.m. on April 15, 1865.[citation needed]