What advantage did central-battery ironclads have over high-sided ships such as HMS Warrior?
Short answerThey concentrated thick armor around the fighting center, although Warrior itself also used a strongly protected central zone with lighter ends.
NotesArmor concentration is the central advantage of the battery arrangement. Thick protection could cover the vital fighting area while the bow and stern remained more lightly armored. HMS Warrior already shares much of this principle despite her high-sided appearance. The useful distinction lies in the distribution of armor and guns, rather than the ship's silhouette.