Despite the lengthy design process, the ships proved to be failures in service, primarily as a result of their low speed.

By the 1890s, they were reactivated for training ship duties, and in 1897 Sebenico took part in an international naval demonstration off Crete, where she sank a Greek blockade runner.

Unable to increase the strength of the ironclad fleet, Pöck turned to less expensive means to defend Austria-Hungary's coastline, including development of naval mines and self-propelled torpedoes.

Pöck decided to await a report from then-Fregattenkapitän (Frigate Captain) Hermann von Spaun, the naval attache to Britain, who was observing British developments, including the construction of the torpedo gunboat HMS Vesuvius.

The ship would be capable of a speed of at least 15 knots (28 km/h; 17 mph) from a twin-screw propulsion system, and it would not be equipped with a sailing rig.

They also created an alternate proposal for a smaller, unarmored ship with just two to four light guns, in the event that their preferred vessel could not reach the desired speed.

They argued that an attempt to build what they described as a "universal battle-ship" (i.e., the Schiffbau-Kommission's first proposal) was ill-advised, since torpedoes were still in the developmental phase and a vessel of that type would be expensive and risky, considering the limited budgets of the time.

Alternatively, if submerged tubes could not be made to work on the broadside, the ship should include two deck-mounted launchers with at least five torpedoes apiece, four heavy guns, and a speed sufficient just to keep pace with the ironclads of the main fleet.

A suggestion was made to await developments in torpedo technology and to incorporate the weapons into the next ironclad that they could secure funding from Parliament to build.

Josef von Romako, the Chief Constructor of the Austro-Hungarian Navy, pointed out that such a vessel would have to be very large to allow it to reach high enough speeds for it to be able to use torpedoes effectively.

In the meantime, Spaun made his report on British naval activities, which included the completion of Vesuvius and the introduction of twin-screw propulsion.

He also reported on the construction and sea trials of the British-built torpedo-aviso SMS Zieten for the Imperial German Navy.

Zieten proved to be fast and maneuverable, qualities that made her well-suited to training and development of the German torpedo warfare arm.

On 30 January, Shipbuilding Engineer Andressen began working on the projet, which at that time included a pair of 24 cm (9.4 in) guns in an armored casemate.

Sebenico received the most radical alteration; her stern was lengthened slightly to allow for finer hull lines, which would improve her hydrodynamic shape, though this too failed to provide a significantly higher speed.

They were too slow to be used as fleet scouts or flotilla leaders, and their gun armament was too weak for them to be able to protect torpedo boats from torpedo-boat destroyers.

[16] That year, Sebenico took part in the only significant period of fleet service, when she was sent to the island of Crete to participate in an international naval demonstration during Greco-Turkish War.

[18] Zara was stationed in Cattaro Bay and Sebenico protected the harbor of her namesake city, while Spalato provided local defense outside Pola.

Zara was transferred from Cattaro Bay to Pola in June 1917, but while en route, suffered a serious explosion that caused significant damage to her bow.

A contemporary investigation determined that it was the result of badly deteriorated chemicals in her torpedo warheads, though the naval historian René Greger reports that a mine was actually to blame.