 The ironclad became technically feasible and tactically necessary because of developments in shipbuilding in the first half of the 19th century . According to naval historian J. Richard Hill : " The ( ironclad ) had three chief characteristics : a metal @-@ skinned hull , steam propulsion and a main armament of guns capable of firing explosive shells . It is only when all three characteristics are present that a fighting ship can properly be called an ironclad . " Each of these developments was introduced separately in the decade before the first ironclads . 
 The ironclad became technically feasible and tactically necessary because of developments in shipbuilding in the first half of the 19th century . According to naval historian J. Richard Hill : " The ( ironclad ) had three chief characteristics : a metal @-@ skinned hull , steam propulsion and a main armament of guns capable of firing explosive shells . It <a href='drop_aux' title='1'><mark>is</mark></a>only when all three characteristics <a href='drop_aux' title='2'><mark>are</mark></a>present that a fighting ship can properly be called an ironclad . " Each of these developments was introduced separately in the decade before the first ironclads . 
The ironclad became technically feasible and tactically necessary cuz of developments in shipbuilding in da first half of tda19th century . According to naval historian J. Richard Hill : " Thda ironclad ) had three chief characteristics : a metal @-@ skinned hull , steam propulsion and a main armament of guns capable of firing explosive shells . It only when all three characteristics present that a fightin ship can properly be called an ironclad . " Each of dem developments was introduced separately in the decade b4 thedarst ironclads .