Civil War Union Brigadier General. Born in Boston, Massachusetts, he was appointed to the United States Military Academy at West Point, New York in 1825, graduating 5th out of forty nine in 1829 ranking (he was one of the few cadets in the history of the Academy not to have incurred a demerit while attending). First assigned as an Assistant Teacher of French at the Academy, in 1830 when he was a 1st Lieutenant, he was detailed to the 4th United States Artillery, taking part in the Black Hawk expedition in 1832. He was subsequently stationed in Charleston Harbor, South Carolina and at Fort McHenry, Baltimore, Maryland. In 1833 Barnes was again detailed for duty at West Point, where he was assigned to the Department of Infantry Tactics, a position he held for three years before reassignment. He resigned his commission with the Army in 1836 and took employment as a railroad engineer, later served as superintendent on the Western railroad of Massachusetts from 1836 to 1848. Between 1848 and 1857 he supervised construction of railroads in New York State, Indiana, Illinois, and Missouri. At the outbreak of the Civil War he applied for a commission In the Union Army and was appointed Colonel of the 18th Massachusetts Volunteer Infantry on July 26, 1861. He led the regiment during the May 1862 Siege of Yorktown, Virginia and continued in this capacity until July 14, 1862, when placed in command of the 1st Brigade, 1st Division, Fifth Corps, Army of the Potomac, seeing action at the Battles of Antietam, Shepardstown, and Fredericksburg. Promoted to the rank of Brigadier General, US Volunteers in November 1862, he was particularly recognized and commended for his command actions during the December 1862 Battle of Fredericksburg. Just prior to the July 1863 Battle of Gettysburg, General Barnes was temporarily placed in command of 1st Division of the Fifth Corps, then under command of General Charles Griffin. Controversy has since swirled around Barnes regarding his actions on the second day of the Battle of Gettysburg (July 2, 1863) including allegations that he was intoxicated. He was, in fact, wounded in the left leg by a shell fragment and after lying unconscious for a period as his Division fought in the bloody Wheatfield area, he continued in command until relieved by General Griffin. General Barnes rejoined the Division in August 1863 after a leave of absence, but was relieved from further combat command and relegated to lesser positions, including assignments as the military commander of Norfolk and Portsmouth, Virginia district and from July 1864 the St. Mary's District in Maryland. He was brevetted Major General, US Volunteers on March 13, 1865 and continued in military service until mustered out on January 15, 1866. He returned to Springfield, Massachusetts and in January 1868 was appointed as a Special Commissioner to investigate charges of scandal and defective construction in the building of the Transcontinental Railroad. Beset by continuing health issues, he fared poorly and died in Springfield at the age of 62.