The Austro-Hungarian Empire's retention of a territorial foothold at the head of the Adriatic necessitated a small navy which, by 1900, was attempting to keep pace with those of the other Great Powers, particularly Italy. When that country began building her first "Dreadnought" battleship in June 1909, Austria-Hungary lost no time in ordering four of her own and although the nameship of the "Tegetthoff" class was begun in Septmeber 1910, the flagship Viribus Unitis was actually laid down two months earlier on 24th July. Built, along with two of her sisters, by Stabilimento Technico Triestino at Triest, Viribus was launched on 24th June 1911 and finally completed on 5th December 1912. Designed to displace 20,013 tons (21,595 deep loaded), she measured 499 feet in length overall with an 89 foot beam, and her hull was protected by a belt of armour ranging from 6 to 11ins. in thickness. She caried 12-12in. guns as her main armourment but also had twin torpedo tubes fore and aft coupled with some anti-aircraft small calibre weapons fitted in 1914. Powered by 4-shaft Parsons' geared turbines fired from 12 Yarrow boilers, her engines developed 27,000shp. to give her a maximum speed of 20.3 knots and she had bunkers for 2,000 tons of coal. From a technical standpoint, she and the other "Tegetthoff's" were both compact and powerful and Viribus herself was the world's first "Dreadnought" to enter service with 12in. triple turrets.

In the spring of 1914, Viribus and her newly completed sister Tegetthoff undertook their only foreign tour and the trip around the ports of the Eastern Mediterranean including a week's stay in Malta as guests of the the Royal Navy. These peacetime junkets were rapidly coming to an end however and when Archduke Franz Ferdinand and his wife were assassinated in Sarajevo on 28th June 1914, the world's eyes looked on as Viribus played out her rle in the unfolding crisis. After a brief lying-in-state at Sarajevo, the Archducal bodies were taken to Metkovic by special train and thence to the Narenta estuary by imperial yacht; there they were taken aboard Viribus which proceeded slowly and under escort along the Dalmatian Coast to Trieste from whence the cortge travelled overland to Vienna. It was a moment of high drama in international affairs and, within weeks, all Europe became embroiled in the ensuing War.

When the Great War began, the Austro-Hungarian Navy found itself ranged against the might of the British Mediterranean Fleet and wisely kept to its base a Pola. Once Italy entered the War on the Allied side on 24th May 1915 however, a flotilla led by Viribus immediatley put to sea and, in the opening hours of hostilities, bombarded many Italian shore facilities, including the strategic coastal railway line around Ancona, thereby delaying the initial Italian land offensive by several days. Returning to Pola, the flotilla did not venture out again once their Italian opponents had been mobilized. Apart from the operation to attack the Otranto barrage in June 1918, aborted at the last moment by the sinking of another of Viribus's sisters, the Austro-Hungarian ships came out only on practice runs although it has been argued that their mere presence as a deterrent kept Austria's Adriatic coast free from allied invasion for the duration of the War. On 1st November 1918, by which time the Hapsburg dynasty had collapsed and the imperial fleet handed over to the South-Slavic (Yugoslavian) National Council, two Italian frogmen penetrated Pola harbour and attached a limpit mine to Viribus; when it exploded, the flagship capsized and took down with her not only her commander and 400 lives, but also all of Austria's remaining pretentions as a naval power.