With the outbreak of war, Chambliss was commissioned colonel of the
13th Virginia Cavalry in July 1861. Until the fall of 1862 he was under the orders of Maj. Gen.
D. H. Hill, in the department south of the
James River. During the
Maryland Campaign, he was put in command of the forces on the
Rappahannock River, between
Warrenton and
Fredericksburg, with the 13th Virginia,
2nd North Carolina Cavalry, and
61st Virginia Infantry. He received a commendation for his performance from General
Robert E. Lee. In November he was assigned with his regiment to
Fitzhugh Lee's cavalry
brigade. In April 1863, when the cavalry corps of the
Union Army of the Potomac attempted to cross the Rappahannock and cut General Lee's communications with
Richmond, Chambliss was particularly prominent in turning back this movement. At Beverly Ford with 50 men, he drove two Federal squadrons into the river, capturing a number of prisoners. He and his men were commended for bravery by generals Robert. E. Lee and
J.E.B. Stuart. ==Gettysburg Campaign, 1864==