When Austria-Hungary was facing defeat in the war in October 1918, the Austrian government decided to transfer Viribus Unitis to the newly formed State of Slovenes, Croats and Serbs in order to avoid having to hand the ship over to the Allied Powers.

However, 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.

The value of pre-dreadnought battleships declined rapidly and numerous ships in European navies were rendered obsolete, giving Austria-Hungary an opportunity to make up for past neglect in naval affairs.

[37] In his memoirs, former Austrian Field Marshal and Chief of the General Staff Conrad von Hötzendorf wrote that due to his belief in a future war with Italy, construction on the battleships should begin as soon as possible.

[38] Facing potential backlash over constitutional concerns that the construction of the first two battleships committed Austria-Hungary to spend roughly 120 million Kronen without prior approval by either the Austrian Reichsrat or the Diet of Hungary, the deal remained secret.

[39] In the event of the agreement being leaked to the press prior to the passage of a new naval budget, Montecuccoli drafted several explanations to justify the battleships' construction and the necessity to keep their existence a secret.

[40] By the time the agreement was leaked to the public in April 1910 by the Arbeiter-Zeitung, the newspaper of Austria's Social Democratic Party, the plans had already been finalized and construction on the first two battleships, Viribus Unitis and Tegetthoff, was about to begin.

This was done in order to rush the completion of the Radetzky-class battleships, though the looming construction of four dreadnoughts meant the Austro-Hungarian Navy would likely have to ask the government for a yearly budget much higher than 100 million Kronen.

[41][42] The budgets providing funding for the Tegetthoff class were finally approved after two meetings of the Austrian Reichsrat and the Diet of Hungary in October and November 1910, with opposition being rejected as the Italian Navy had laid down another three battleships during the summer.

The final package included provisions which ensured that while the armor and guns of the Tegetthoff class were to be constructed within Austria, the electrical wiring and equipment aboard each ship was to be assembled in Hungary.

"[57] While Popper adopted several of Tirpitz's suggestions regarding the external layout of the belt armor for the Tegetthoff class, the internal modifications put forward by the Imperial German Navy were not implemented.

The naval commission investigating the loss of the battleship ultimately concluded: "The distance between mine armor and 15-cm-ammunition magazines is too small and a major design failure, which most probably caused the widening of the leak.

"[56] Following Szent István's sinking, it was also discovered that her propeller shafts had such a high degree of resistance that the ship's rudder could only be laid at a maximum angle of 10° at full speed or else she would suffer from a heavy list.

[63] These concerns continued to grow and in April 1909 British Ambassador Fairfax Leighton Cartwright asked Austro-Hungarian Foreign Minister Alois Lexa von Aehrenthal about the rumored battleships.

[64] Neither the Admiralty's suspicions, nor those of some politicians, managed to convince the British Parliament that the German government was attempting to use the Tegetthoff class to escalate Germany and Britain's already contentious naval arms race.

[67] The Christian Social Party, supportive of the construction of the ships and operating on the advice of the navy, published in its own newspaper, Reichspost, that the secret dreadnought project and related financial agreements were true.

[69][8] Less than a year after being laid down in Trieste, Viribus Unitis was launched on 24 June 1911 at a large ceremony featuring Archduke Franz Ferdinand and the Austrian Minister of War, General Moritz von Auffenberg.

[8][71] Despite strikes in August 1912 and March 1913 by mechanics working on her engines,[72] Prinz Eugen was launched on 30 November, while construction on Szent István took longer due to the fact that the shipyards in Fiume had to be expanded for a ship of her size.

[3] Prior to World War I, the Tegetthoff class served as the pride of the Austro-Hungarian Navy, conducting several voyages throughout the Adriatic and Mediterranean Seas as members of the 1st Battle Division under the command of Vice-Admiral Maximilian Njegovan.

[78] In the spring of 1914 Viribus Unitis and Tegetthoff, together with Zrínyi and the coastal defense ship Monarch, traveled the eastern Mediterranean, the Sea of Sicily, and the Levant, visiting the ports of Smyrna, Beirut, Alexandria, and Malta.

[84] Upon hearing of the assassination, Commander-in-Chief of the Navy Anton Haus sailed south from Pola with an escort fleet comprising Tegetthoff, the scout cruiser Admiral Spaun, and several torpedo boats.

While relations between Austria-Hungary and Italy had improved greatly in the two years following the 1912 renewal of the Triple Alliance,[88] 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.

Even so, the necessity of ensuring the navy's most important ships such as the Tegetthoffs had the coal they needed in the event of an Italian or French attack or a major offensive operation resulted in the dreadnoughts remaining at port unless circumstances necessitated their deployment at sea.

Horthy's strategic thinking differed from his two predecessors, and shortly after assuming command of the navy he resolved to undertake a major fleet action in order to address low morale and boredom, and make it easier for Austro-Hungarian and German U-boats to break out of the Adriatic into the Mediterranean.

[125] En route to the harbour at Islana, north of Ragusa, to rendezvous with 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.

The low death toll can be partly attributed to the long amount of time it took for the battleship to sink, and the fact that all sailors with the Austro-Hungarian Navy had to learn to swim before entering active service.

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.

[138] 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.

She was first subject to test aerial bombardment attacks and later sunk by the battleships Paris, Jean Bart, and France off Toulon on 28 June 1922, exactly eight years after the assassination of Archduke Franz Ferdinand.

[154] In reference to her originally planned name and in homage to the Austro-Hungarian Navy, the bell from Tegetthoff was presented to the German cruiser Prinz Eugen on 22 November 1942 by the Italian Regia Marina.