SMS Don Juan d'Austria (1862)

Map showing the disposition of the fleets on 20 July

On 16 July, Persano took the Italian fleet, with twelve ironclads, out of Ancona, bound for the island of Lissa, where they arrived on the 18th. With them, they brought troop transports carrying 3,000 soldiers.[4] Persano then spent the next two days bombarding the Austrian defenses of the island and unsuccessfully attempting to force a landing. Tegetthoff received a series of telegrams between 17 and 19 July notifying him of the Italian attack, which he initially believed to be a feint to draw the Austrian fleet away from its main bases at Pola and Venice. By the morning of the 19th, however, he was convinced that Lissa was in fact the Italian objective, and so he requested permission to attack. As Tegetthoff's fleet arrived off Lissa on the morning of 20 July, Persano's fleet was arrayed for another landing attempt. The latter's ships were divided into three groups, with only the first two able to concentrate in time to meet the Austrians. Tegetthoff had arranged his ironclad ships into a wedge-shaped formation, with Don Juan d'Austria on his right flank; the wooden warships of the second and third divisions followed behind in the same formation.[6]

While he was forming up his ships, Persano transferred from his flagship, Re d'Italia, to the turret ship Affondatore. This created a gap in the Italian line, and Tegetthoff seized the opportunity to divide the Italian fleet and create a melee. He made a pass through the gap, but failed to ram any of the Italian ships, forcing him to turn around and make another attempt. Don Juan d'Austria initially attempted to follow Tegetthoff's flagship, Erzherzog Ferdinand Max, but quickly lost contact with her in the ensuing melee. Don Juan d'Austria became surrounded by Italian vessels, prompting her sister Kaiser Max to come to her aid. Don Juan d'Austria thereafter engaged Re di Portogallo for around half an hour before shifting targets back to Affondatore. The latter scored three hits on Don Juan d'Austria's unarmored bow, but they caused little damage. The first passed directly through the ship without exploding, the second struck the belt armor and failed to penetrate, and the third hit her quarter deck.[7]

By this time, Re d'Italia had been rammed and sunk and the coastal defense ship Palestro was burning badly, soon to be destroyed by a magazine explosion. Persano broke off the engagement, and though his ships still outnumbered the Austrians, he refused to counter-attack with his badly demoralized forces. In addition, the fleet was low on coal and ammunition. The Italian fleet began to withdraw, followed by the Austrians; Tegetthoff, having gotten the better of the action, kept his distance so as not to risk his success. As night began to fall, the opposing fleets disengaged completely, heading for Ancona and Pola, respectively.[8]

After returning to Pola, Tegetthoff kept his fleet in the northern Adriatic, where it patrolled against a possible Italian attack. The Italian ships never came, and on 12 August, the two countries signed the Armistice of Cormons; this ended the fighting and led to the Treaty of Vienna. Though Austria had defeated Italy at Lissa and on land at the Battle of Custoza, the Austrian army was decisively defeated by Prussia at the Battle of Königgrätz. As a result, Austria, which became Austria-Hungary in the Ausgleich of 1867, was forced to cede the city of Venice to Italy. In the immediate aftermath of the war, the bulk of the Austrian fleet was decommissioned and disarmed.[9]

The fleet embarked on a modest modernization program after the war, primarily focused on re-arming the ironclads with new rifled guns.[10] Don Juan d'Austria was rebuilt in 1867, particularly to correct her poor sea-keeping. Her open bow was plated over and she was rearmed with twelve 7-inch (178 mm) muzzle-loaders manufactured by Armstrong and two 3-inch (76 mm) 4-pounder guns. By 1873, the ship was obsolescent and had a thoroughly-rotted hull, so the Austro-Hungarian Navy decided to replace the ship. Parliamentary objection to granting funds for new ships forced the navy to resort to subterfuge to replace the ship. Reconstruction projects were routinely approved by the parliament, so the navy officially "rebuilt" Don Juan d'Austria and her sister ships. In reality, only some parts of the engines, armor plate, and other miscellaneous parts were salvaged from the ships. Don Juan d'Austria was dismantled at the STT shipyard beginning in December 1873. The new ironclads were given the same names of the old vessels in an attempt to conceal the deception.[11]