Principe Amedeo was an ironclad warship built by the Italian Regia Marina in the 1860s and 1870s. She was the lead ship of the Principe Amedeo class, alongside her sister ship Palestro. Principe Amedeo was laid down in 1865, launched in 1872, and completed in late 1874. She was armed with a battery of six 254 mm (10 in) guns and one 279 mm (11 in) gun. The last sail-rigged ironclad of the Italian fleet, she had a single steam engine that was capable of propelling the ship at a speed of slightly over 12 knots.

Castelfidardo was the third of four Regina Maria Pia-class ironclad warships built in French shipyards for the Italian Regia Marina in the 1860s. Castelfidardo was laid down in July 1862, was launched in August 1863, and was completed in May 1864. She and her three sister ships were broadside ironclads, mounting a battery of four 203 mm (8 in) and twenty-two 164 mm (6.5 in) guns on the broadside.