While cast iron has never been used for naval armour, it did find a use in land fortifications, presumable due to the lower cost of the material. One well known example of cast-iron armour for land use is the Gruson turret, first tested by the Prussian government in 1868. Armoured ships may have been built as early as 1203, in the far east.
Cast iron has never been used in naval protection, but it was applied to land defensive structures due to its lower cost. The Gruson turret, first tested by the Prussian government in 1868, is a notable example of cast-iron armour for land use. Armoured ships may have existed as early as 1203 in distant eastern regions.