Events on June 10 in history

The Austro-Hungarian battleship SMS Szent István sinks off the Croatian coast after being torpedoed by an Italian MAS motorboat; the event is recorded by camera from a nearby vessel.

SMS Szent Istvn (His Majesty's Ship Saint Stephen) was the last of four Tegetthoff-class dreadnought battleships built for the Austro-Hungarian Navy. Szent Istvn was the only ship of her class to be built within the Hungarian part of the Austro-Hungarian Empire, a concession made to the Hungarian government in return for its support for the 1910 and 1911 naval budgets which funded the Tegetthoff class. She was built at the Ganz-Danubius shipyard in Fiume, where she was laid down in January 1912. She was launched two years later in 1914, but Szent Istvn's construction was delayed due to the smaller shipyards in Fiume, and further delayed by the outbreak of World War I in July 1914. She was finally commissioned into the Austro-Hungarian Navy in December 1915.

Armed with a main battery of twelve 30.5 cm (12.0 in) guns in four triple turrets, Szent Istvn was assigned to the 1st Battleship Division of the Austro-Hungarian Navy upon her commissioning. Alongside the other ships of her class, she was stationed out of the Austro-Hungarian naval base at Pola. Szent Istvn's commissioning into the fleet came too late for her to participate in the Bombardment of Ancona following Italy's declaration of war on Austria-Hungary in May 1915, and she saw little combat for the rest of the war due to the Otranto Barrage, which prevented the Austro-Hungarian Navy from leaving the Adriatic Sea.

In June 1918, in a bid to ensure safer passage for German and Austro-Hungarian U-boats through the Strait of Otranto, the Austro-Hungarian Navy attempted to break the Barrage. This attack was to be spearheaded by all four ships of the Tegetthoff class but was abandoned after Szent Istvn and her sister ship, Tegetthoff were attacked by Italian motor torpedo boats on the morning of 10 June. While Tegetthoff was unharmed, Szent Istvn was struck by two torpedoes launched from MAS-15, and capsized roughly three hours later off the island of Premuda. She is the only battleship whose sinking was filmed during World War I.

The ship's wreck was located in the mid-1970s by the Yugoslav Navy. She lies upside down at a depth of 66 metres (217 ft). Her bow broke off when it hit the seabed while the stern was still afloat, but is immediately adjacent to the rest of the heavily encrusted hull. She is a protected site of the Croatian Ministry of Culture.

The Austro-Hungarian Navy or Imperial and Royal War Navy (German: kaiserliche und königliche Kriegsmarine, in short k.u.k. Kriegsmarine, Hungarian: Császári és Királyi Haditengerészet) was the naval force of Austria-Hungary. Ships of the Austro-Hungarian Navy were designated SMS, for Seiner Majestät Schiff (His Majesty's Ship). The k.u.k. Kriegsmarine came into being after the formation of Austria-Hungary in 1867, and ceased to exist in 1918 upon the Empire's defeat and subsequent collapse at the end of World War I.

Prior to 1867, the Imperial Austrian Navy or simply the Austrian Navy, saw action in the French Revolutionary Wars, the Napoleonic Wars, the Austrian expedition against Morocco (1829), the Second Egyptian–Ottoman War, the First and Second Wars of Italian Independence, the Second Schleswig War, and the Third War of Italian Independence. Following Austria's defeat by Prussia and Italy during the Seven Weeks' War, the Austrian Empire reformed itself into the dual monarchy of Austria-Hungary, and the navy also became the Austro-Hungarian Navy. Largely neglected by the Empire in its early years, the k.u.k. Kriegsmarine expanded along with Austro-Hungarian industrialization into one of the largest navies in the Adriatic and Mediterranean Seas. By 1914, the k.u.k. Kriegsmarine had a peacetime strength of 20,000 personnel, seeing action in the Boxer Rebellion and other conflicts prior to World War I.

During most of World War I, the Allied Powers maintained the Otranto Barrage to bottle up the k.u.k. Kriegsmarine in the Adriatic Sea. Largely tasked with defending the Empire's 1,130 nautical miles (2,090 km; 1,300 mi) of coastline and 2,172.4 nautical miles (4,023.3 km; 2,500.0 mi) of island seaboard, the Navy chose to rely on its U-boats to attack Allied shipping rather than risk the destruction of its battleships, cruisers and other surface vessels. In June 1918, it attempted to break the Otranto Barrage with a large naval fleet, but the attack was called off after the battleship Szent István was sunk by an Italian torpedo boat on 10 June.

Five months later, with the Austro-Hungarian Empire facing collapse and defeat in the war, the Empire decided to transfer most of its navy to the newly declared State of Slovenes, Croats and Serbs on 31 October, effectively bringing the k.u.k. Kriegsmarine to an end. Three days later, the Empire's military authorities signed the Armistice of Villa Giusti, pulling the rapidly disintegrating empire out of the war. With the signing of the Treaty of Saint-Germain-en-Laye and the Treaty of Trianon, Austria and Hungary became landlocked, and the Empire's most important ports of Trieste, Pola, Fiume and Ragusa became part of Italy and Yugoslavia. The k.u.k. Kriegsmarine's main ships were turned over to the Allies, who scrapped most of them in the 1920s during the era of naval disarmament.