When the Civil War came, the Tredegar Iron Company emerged as the industrial heart of the Confederate States of America. Using slave and free labor, Anderson supervised ordnance and munitions production through most of the war.
Anderson, a supporter of southern secession and states' rights, was commissioned a major of artillery in August 1861, and promoted to brigadier general in the Confederate Army on September 3.[2] Initially assigned to command the Confederate forces at Wilmington, North Carolina, in April 1862, he was reassigned to the area around Fredericksburg, Virginia, opposite Union Maj. Gen. Irvin McDowell.
With the mounting threat to Richmond during the Peninsula Campaign, Anderson was placed in command of the 3rd Brigade in A.P. Hill's newly formed "Light Division." During the Seven Days Battles, he led his brigade at Mechanicsville, Gaines Mill, and Glendale, where he received a concussion from being hit in the head by a spent musket ball. Anderson was left disoriented and confused by the incident and spent the next few weeks recovering.
General Anderson resigned his army commission on July 19, 1862, and served the Confederate war effort in the Ordnance Department until the evacuation of Richmond on the night of April 2–3, 1865. As the retreating Confederate troops burned many of the munitions dumps and industrial warehouses that would have been valuable to the North, Anderson reportedly paid over fifty armed guards to protect the Tredegar facility from arsonists.[4] As a result, the Tredegar Iron Works is one of few Civil War era buildings in the warehouse district that survived the burning of Richmond.