Throughout the rest of 1915 and 1916, all three ships saw extensive combat in several raids directed at the Otranto Barrage which prohibited the bulk of the Austro-Hungarian Navy from leaving the Adriatic Sea.

Emboldened by this operation and determined to break the Otranto Barrage with a major attack on the strait, Austria-Hungary's newly appointed Commander-in-Chief of the Fleet (German: Flottenkommandant) Miklós Horthy de Nagybánya organized a massive attack on the Allied forces with the three Novara-class cruisers, alongside seven battleships, one cruiser, four destroyers, four torpedo boats, and numerous submarines and aircraft, but the operation was abandoned after the battleship Szent István was sunk by the motor torpedo boat MAS-15 on the morning of 10 June.

When Austria-Hungary was facing defeat in October 1918, the Austrian government transferred its navy to the newly formed State of Slovenes, Croats and Serbs in order to avoid having to hand the ship over to the Allies.

[8] The Novara-class cruisers were developed at a time when Austria-Hungary's naval policy began to shift away from simply coastal defense, to projecting power into the Adriatic and even Mediterranean Seas.

New railroads had been constructed through Austria's Alpine passes between 1906 and 1908, linking Trieste and the Dalmatian coastline to the rest of the Empire and providing the interior of Austria-Hungary with quicker access to the sea than ever before.

The appointment of Archduke Franz Ferdinand – heir to the Austro-Hungarian throne and a prominent and influential supporter of naval expansion – to the position of admiral in September 1902 greatly increased the importance of the navy in the eyes of both the general public and the Austrian and Hungarian Parliaments.

[10][11] Franz Ferdinand's interest in naval affairs stemmed primarily from his belief that a strong navy would be necessary to compete with Italy, which he viewed as Austria-Hungary's greatest regional threat.

[18] tonnage ratio The Novara-class ships were first conceived on paper in early 1905 when Montecuccoli drafted his first proposal for a modern Austrian fleet as part of his plan to construct a navy large enough to contest the Adriatic Sea.

[19][20] While the Austrian and Hungarian Delegations for Common Affairs approved Montecuccoli's program in part at the end of 1905, the budget only included for the three Erzherzog Karl-class battleships, the cruiser Admiral Spaun, and six destroyers.

[21] Taking advantage of political support for naval expansion he had obtained in both Austria and Hungary since coming into office, and Austrian fears of a war with Italy over the Bosnian Crisis during the previous year, Montecuccoli drafted a new memorandum to Emperor Franz Joseph I in January 1909 proposing an enlarged Austro-Hungarian Navy consisting of 16 battleships, 12 cruisers, 24 destroyers, 72 seagoing torpedo boats, and 12 submarines.

By this time, some of the dreadnought battleships in his plan, Viribus Unitis and Tegetthoff, had already been laid down, effectively forcing the hand of the remaining members of the Austro-Hungarian government who opposed Montecuccoli's project.

Despite heated debate among the deputies, including an attempt to kill the proposal outright and initiate talks with Italy to end the growing arms race between Austria-Hungary and its nominal ally, the vast majority of both the Austrian and Hungarian delegations supported Montecuccoli's plan to expand the navy.

These turbines were designed to provide 25,600 shaft horsepower (19,100 kW) and were powered by 16 Yarrow water-tube boilers, giving the Novara-class ships a top speed of 27 knots (50 km/h; 31 mph).

While relations between Austria-Hungary and Italy had improved greatly in the two years following the 1912 renewal of the Triple Alliance,[38] increased Austro-Hungarian naval spending, political disputes over influence in Albania, and Italian concerns over the potential annexation of land in the Kingdom of Montenegro caused the relationship between the two allies to falter in the months leading up to the war.

[40] In response to these events, the Austro-Hungarian Navy decided to suspend any outstanding orders or construction projects on new warships, returning the monetary savings back to the Ministry of Finance for use in the war, which at the time was expected to be over in a matter of months.

[45][46] The two Novara-class ships in service at the time had been commissioned too late to participate in Austria-Hungary's naval maneuvers in support of the battlecruiser Goeben and light cruiser Breslau.

[48] This concern was so great to Haus that he wrote in September 1914, "So long as the possibility exists that Italy will declare war against us, I consider it my first duty to keep our fleet intact.

On 20 May, Emperor Franz Joseph I gave the Austro-Hungarian Navy authorization to attack Italian ships convoying troops in the Adriatic or sending supplies to Montenegro.

[64] To facilitate further raids against Italian shipping, Helgoland, Novara, six Tátra-class destroyers, six 250t-class T-group torpedo boats and an oiler were transferred to Cattaro on 29 November.

Dartmouth opened fire with her 6-inch (152 mm) guns at a range of 10,600 yards (9,700 m) and Horthy ordered his ships to lay a smoke screen several minutes later.

Helgoland and six destroyers tried to duplicate the attack with another raid on the night of 18 October, but they were spotted by Italian aircraft and turned back in the face of substantial Allied reinforcements.

Liechtenstein and Erich von Heyssler, the commander of Helgoland, discussed overnight how to extricate their vessels, their crews having abstained from actively supporting the rebels.

Liechtenstein tore down the red flag before ordering his ship to escape into the inner harbor; they were joined by the other scout cruisers and most of the torpedo boats, followed by several of the other larger vessels.

[94] En route to the harbor at Islana, north of Ragusa, to rendezvous with the battleships Viribus Unitis and Prinz Eugen for the coordinated attack on the Otranto Barrage, Szent István and Tegetthoff attempted to make maximum speed in order to catch up to the rest of the fleet.

Thus Emperor Karl I's government in Vienna asked the newly formed State of Slovenes, Croats and Serbs for help maintaining the fleet stationed at Pola and keeping order among the navy.

[102] Emperor Karl I, still attempting to save the Empire from collapse, agreed to the transfer, provided that the other "nations" which made up Austria-Hungary would be able to claim their fair share of the value of the fleet at a later time.

The transfer to the State of Slovenes, Croats and Serbs began on the morning of 31 October, with Horthy meeting representatives from the South Slav nationalities aboard his flagship, Viribus Unitis in Pola.

[105] Control over the battleship, and the head of the newly-established navy for the State of Slovenes, Croats and Serbs, fell to Captain Janko Vuković, who was raised to the rank of admiral and took over Horthy's old responsibilities as Commander-in-Chief of the Fleet.

At a conference at Corfu, the Allied Powers agreed the transfer of Austria-Hungary's Navy to the State of Slovenes, Croats and Serbs could not be accepted, despite sympathy from the United Kingdom.

Following her disarmament, Brindisi was used as a depot ship at Ancona, Pula, and Trieste until she was stricken from the Navy List on 11 March 1937 and sold for scrapping alongside Venezia.