Known in the regular army as "Tardy George," George Sykes was removed from a corps command in the Army of the Potomac's spring 1864 reorganization; Grant had made his headquarters with that force and determined that Sykes was not the man he wanted for the offensive operations he planned. A Delaware native and West Pointer (1842), Sykes was a veteran of infantry service in both the Seminole and Mexican wars, earning a brevet in the latter.
The regular's service in the Civil War included: captain, 3rd Infantry (since September 30, 1855); major, 14th Infantry (May 14, 1861); commanding Reserve Infantry Brigade, Army of the Potomac (August 186 1-March 13, 1862); brigadier general, USV (September 28, 1861); commanding Infantry Reserve, Army of the Potomac (March 13 - May 1862); commanding 2nd Division, 5th Corps, Army of the Potomac (March 18-December 1862 and January-June 28, 1863); major general, USV (November 29, 1862); commanding the corps (February 1-5, 16-23, and June 28 - October 7, 1863 and October 15, 1863 - March 23, 1865); lieutenant colonel, 5th Infantry (October 16, 1863); and commanding District of South Kansas, Department of Kansas (September 1 - October 10, 1864).
At 1st Bull Run he commanded the only regular army infantry on the field, an eight-company battalion from various regiments, and was highly effective in slowing the rout of the volunteers. He then commanded the regulars near Washington and in the midst of the Peninsula Campaign was given charge of a division composed mostly of regular army units. He had already fought at Yorktown and in divisional command participated in the Seven Days fighting. He was at 2nd Bull Run and in reserve at Antietam. Given a second star in the volunteer service, he fought at Fredericksburg and Chancellorsville before taking charge of the 5th Corps upon George G. Meade's assumption of army command just prior to Gettysburg. There he fought in support of the hard-pressed 3rd Corps on the second day. That fall, in the Bristoe and Mine Run campaigns, he behaved true to his nickname and was found lacking by Meade.
Prior to the Wilderness Campaign, Meade and Grant agreed upon his replacement and Sykes finished the war in Kansas. Mustered out of the volunteer service on January 15, 1866, he reverted to his regular army rank and died on active duty in Texas as colonel, 20th Infantry, and brevet major general for the war.
Source: "Who Was Who In The Civil War" by Stewart Sifakis