Formidabile-class ironclad

The Formidabile class was a pair of ironclad warships built for the Italian Regia Marina (Royal Navy) in the 1860s. The class comprised two ships, ITALIAN IRONCLAD Formidabile and ITALIAN IRONCLAD Terribile. They were the first ironclads built for the Italian fleet.

Design
The two ships of the Formidabile class were ordered by Camillo Benso, Count of Cavour, then both the Prime Minister and Naval Minister of the Kingdom of Sardinia in 1860, shortly before the unification of Italy. The ships were originally intended to be armored floating batteries, but they were redesigned as sea-going ironclads after construction began. These ships were the first components of a major naval expansion program that was designed to prepare a fleet of ironclad warships capable of defeating the Austrian Navy. Italy considered the Austrian Empire to be its main rival, since it controlled predominantly Italian areas, including Venice.

General characteristics and machinery
The Formidabile-class ships were wooden-hulled vessels, sheathed with wrought iron armor that was 4.3 in thick. They were 63.05 m long between perpendiculars and 65.8 m and long overall. They had a beam of 14.44 m and an average draft of 5.45 m. The ships displaced 2682 MT normally and up to 2807 MT at full load. Each vessel had a crew of 371 officers and enlisted men.

Their propulsion system consisted of one single-expansion steam engine that drove a single screw propeller, with steam supplied by six coal-fired, rectangular boilers. The boilers were trunked into a single funnel. Their engines produced a top speed of 10 kn from 1080 ihp, though Terribile's boilers produced a slightly higher horsepower, at 1100 ihp. They could steam for about 1300 nmi at their top speed. To supplement the steam engine, the ships were schooner-rigged with three masts.

Armament
The ships of the Formidabile class were originally intended to be armed with thirty guns, but after their conversion to sea-going broadside ironclads, their armament was reduced to twenty guns. These consisted of four 203 mm guns and sixteen 164 mm rifled muzzle-loading guns. Their armament was revised several times throughout their careers. In 1878, both ships had their battery reduced to eight 203 mm guns. Terribile was re-armed with two 6 in guns, two 5.9 in guns, and four 4.7 in guns for service as a training ship in 1885. Two years later, Formidabile was similarly converted into a training ship, equipped with only six 4.7 in guns.