Originally, a vessel of the Mediterranean propelled by
   sails and by oars. The French, about 1650, transferred the name to
   larger vessels, and by 1750 it had been appropriated for a class of war
   vessels intermediate between corvettes and ships of the line. Frigates,
   from about 1750 to 1850, had one full battery deck and, often, a spar
   deck with a lighter battery. They carried sometimes as many as fifty
   guns. After the application of steam to navigation steam frigates of
   largely increased size and power were built, and formed the main part
   of the navies of the world till about 1870, when the introduction of
   ironclads superseded them.