The naval battle lasted two days. The first day saw the debut of the Virginia and was fought without the Monitor. Havoc was wreaked upon the wooden Union ships and the day ended with the Confederate side at a decided advantage. However, on the second day the Monitor arrived and initiated the famous action known as the duel of the ironclads. Although the battle was inconclusive, it is significant in naval history. Prior to then, nearly all warships were made primarily of wood. After the battle, design of ships and naval warfare changed dramatically, as nations around the world raced to convert their fleets to iron, as ironclads had shown themselves to be clearly superior.