Sykes, George was born on October 9, 1822 in Dover, Delaware, United States. Son of William Sykes.
Attended United States Military Academy, 1842.
Commissioned Second lieutenant, 3d Infantry, took part in Seminole War, 1842. First lieutenant in war with Mexico from Vera Cruz to Mexico City, 1846. Brevetted captain for gallant conduct at Battle of Cerro Gordo, 1855.
Major in Civil War, served in 1st Battle of Bull Run, 1861. Commissioned brigadier general United States Volunteers, September 1861. At Malvern Hill, 1862.
Commanded V Corps in Gettysburg campaign, brevetted brigadier general United States Army. Went to Kansas, 1864. Mustered out of the United States volunteers as major general, reverted to rank lieutenant colonel 5th Infantry, United States Army, 1866.