 <unk> were designed for several roles , including as high seas battleships , coastal defense ships , and long @-@ range cruisers . The rapid evolution of warship design in the late 19th century transformed the ironclad from a wooden @-@ <unk> vessel that carried sails to supplement its steam engines into the steel @-@ built , <unk> battleships and cruisers familiar in the 20th century . This change was pushed forward by the development of heavier naval guns ( the ironclads of the 1880s carried some of the heaviest guns ever mounted at sea ) , more sophisticated steam engines , and advances in metallurgy which made steel shipbuilding possible . 
