Erzherzog Ferdinand Max-class ironclad

Following the launch of the French Gloire, the first ironclad warship, the Austrian Navy began a major ironclad construction program under the direction of Archduke Ferdinand Max, the Marinekommandant (naval commander) and brother of Kaiser Franz Josef I.^[1][2] Ferdinand Max envisioned an ironclad fleet of nine ships, which would be powerful enough to both defeat the fleet of the recently unified Kingdom of Italy, and to make Austria an attractive ally to Britain. In late 1860 and 1861, the first five ships—two Drache and three Kaiser Max-class ironclads—were ordered in response to Italian ironclad orders; the Austro-Italian ironclad arms race had begun.^[3]

The construction of the Drache and Kaiser Max classes prompted the Austrian government to convene a commission in early 1862 to study future naval development, and crucially, the question of whether the navy should be oriented toward power projection from the Adriatic or purely defensive of the Austrian Littoral. The commission had deadlocked by April, but the recent Battle of Hampton Roads in the American Civil War—the first engagement between two ironclads—had demonstrated the ascendancy of the new ships and convinced the Reichsrat (Imperial Council) to grant a significant increase for the naval budget, which allowed two new ironclads to be ordered in 1863, which became the Erzherzog Ferdinand Max class.^[4]

All of these ships were designed by the Director of Naval Construction Josef von Romako, who also prepared the design for what became the Erzherzog Ferdinand Max class, named for the Marinekommandant.^[5] These two ships were significantly larger than the Drache and Kaiser Max-class vessels, and were originally intended to carry thirty-two 48-pounder muzzle-loading guns, though during the construction process the Navy decided to opt for a battery of new breech-loading guns manufactured by Krupp. The outbreak of the Seven Weeks' War in 1866 forced the Navy to hastily complete them with only sixteen of the original 48-pounders.^[5][6] They also did not initially receive their sailing rig.^[7]

The Erzherzog Ferdinand Max-class ships had a similar appearance to the French Gloire. The Austrian vessels were 79.97 meters (262 ft 4 in) long between perpendiculars and 83.75 m (274 ft 9 in) long overall. They had a beam of 15.96 m (52 ft 4 in) and an average draft of 7.14 m (23 ft 5 in). They displaced 5,130 long tons (5,210 t). The hulls were of wooden construction, and were sheathed with wrought iron armor that was 123 mm (5 in) thick on the battery and reduced to 87 mm (3.4 in) at the bow and stern. The ships had a crew of 511 officers and enlisted men.^[5]

Their propulsion system consisted of one single-expansion, 2-cylinder, horizontal steam engine that was manufactured by the Stabilimento Tecnico shipyard in Fiume. The engine drove a single screw propeller. The number and type of their coal-fired boilers have not survived, though they were trunked into a single funnel located amidships. Their engines produced a top speed of 12.54 knots (23.22 km/h; 14.43 mph) from 2,925 indicated horsepower (2,181 kW). Coal storage amounted to 330 long tons (340 t). Each ship was fitted with a three-masted rig to supplement the steam engines, but the rushed nature of their completion delayed the installation of the rigging until 1867.^[5][7]

The ships of the Erzherzog Ferdinand Max class were broadside ironclads, and they were armed with a main battery of sixteen 48-pounder muzzle-loading guns. These were carried in the traditional broadside arrangement of earlier ships of the line. They also carried several smaller guns, including four 8-pounder guns and two 3-pounders. Over the course of their career, their armament was revised several times. The old muzzle-loaders were replaced with a battery of fourteen 8 in (203 mm) Krupp guns in 1869. In 1874 they were rearmed with a battery of fourteen 7 in (178 mm) muzzle-loading Armstrong guns and four light guns. Their battery was revised again in 1882, with the addition of four 9 cm (3.5 in) breech-loader guns, two 7 cm (2.8 in) breech-loaders, a pair of 47 mm (1.9 in) quick-firing revolver guns, and three 25 mm (0.98 in) auto-cannons.^[5]