Meanwhile the idea of mounting guns in armored and revolving turrets had been developing. Ships with such features were often termed "monitors", after the USS Monitor of 1862. Ships with flat decks, low freeboards and revolving turrets proved to be effective as coastal harbor guards, but could not survive the heavy seas of the open ocean. A key drawback to this design was that the muzzle-loading guns then in use had to be withdrawn into the turret for reloading. This necessitated very large turrets that were not only cumbersome (several monitors capsized in only moderate seas) but also offered tempting targets to an enemy ship. Attempts to blend turrets with ocean-going hulls produced such freaks as the HMS Agamemnon, which had a turret, placed midway along each side either side of the funnel and superstructure.
from "The Historical Atlas of the World at War" by Rupert Matthews
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