During the Second Schleswig War of 1864, "Don Juan d'Austria" was deployed with the ship of the line and two other vessels to the North Sea, but arrived too late to take part in any fighting, then-Commodore Wilhelm von Tegetthoff having already inflicted a strategic defeat on the Danish squadron at the Battle of Heligoland. All three ships saw action during the Seven Weeks' War that pitted Austria against Prussia and Italy two years later. The war at sea culminated at the Battle of Lissa in July 1866, where all three ships were heavily engaged, though they were not seriously damaged and inflicted little on their Italian opponents. Neither side's ships carried guns strong enough to defeat their opponents armor plating. After the war, the ships were disarmed and laid up.