 The first ironclads were classified as "frigates" because of the number of guns they carried.However, terminology changed as iron and steam became the norm, and the role of the frigate was assumed first by the protected cruiser and then by the light cruiser.Frigates are often the vessel of choice in historical naval novels due to their relative freedom compared to ships-of-the-line (kept for fleet actions) and smaller vessels (generally assigned to a home port and less widely ranging).