The first two vessels of the Principe di Carignano class were initially ordered as steam frigates by the Regia Marina Sarda (Royal Sardinian Navy) shortly before the unification of Italy.
The Principe di Carignano-class ships were broadside ironclads; the lead ship was armed with a main battery of ten 72-pounder guns and twelve rifled muzzle-loading guns Messina and Conte Verde instead carried four 8 in guns and eighteen 164 mm guns.