qnli question: Who commanded the Union armies during the Seven Days Battles? sentence: In addition to Virginia and Confederate government offices and hospitals, a railroad hub, and one of the South's largest slave markets, Richmond had the largest factory in the Confederacy, the Tredegar Iron Works, which turned out artillery and other munitions, including the 723 tons of armor plating that covered the CSS Virginia, the world's first ironclad used in war, as well as much of the Confederates' heavy ordnance machinery.