SM U-12 (Austria-Hungary)

SM U-12 or U-XII was a U-5-class submarine or U-boat built for and operated by the Austro-Hungarian Navy before and during the First World War.

Built on speculation by Whitehead & Co. of Fiume, the submarine was launched as SS-3 in March 1911 and featured improvements in the electrical and mechanical systems from the design by the American John Philip Holland, to which her older sister boats, SMU U-5 (Austria-Hungary) and SMU U-6 (Austria-Hungary), had been built.

SS-3 was laid down in 1909. The double-hulled submarine was just over 105 ft long and displaced between 240 and 273 t, depending on whether surfaced or submerged. Whitehead tried selling SS-3 to several different navies, but she was bought by the Austro-Hungarian Navy after the outbreak of World War I, despite having been rejected by them twice before. She was commissioned as U-12 in August 1914.

The submarine sank only one ship, a Greek cargo ship in May 1915, but she had earlier captured six Montenegrin sailing vessels as prizes in March. U-12 also damaged, but did not sink, the French battleship FRENCH BATTLESHIP Jean Bart in December 1914. While searching for targets in the vicinity of Venice in August 1915, U-12 struck a mine that blew her stern off, and sank with all hands, becoming the first Austro-Hungarian submarine sunk in the war. Her wreck was salvaged the next year by the Italians, who interred U-12's crewmen in a Venetian cemetery.

Design and construction
SS-3 was built on speculation by Whitehead & Co. of Fiume. Her design was based on the John Philip Holland design licensed by Whitehead for SMU U-5 (Austria-Hungary) and SMU U-6 (Austria-Hungary), two submarines ordered by the Austro-Hungarian Navy and built 1907–1910, and featured improvements in the mechanical and electrical systems. SS-3 was laid down in 1909 and launched at Fiume on 14 March 1911.

SS-3's featured a single-hull with a tear-drop shaped body that bore a strong resemblance to modern nuclear submarines. She was 105 ft long by 13 ft abeam and had a draft of 12 ft. She displaced 240 t surfaced, and 273 t submerged. Her two 45 cm bow torpedo tubes featured unique, cloverleaf-shaped design hatches that rotated on a central axis, and the boat was designed to carry up to four torpedoes.

According to one source, SS-3 was initially propelled by a pair of electric motors for surface running, but had them replaced with twin 6-cylinder gasoline engines of 300 bhp each when they proved disappointing during trials. It is not specifically reported for U-12, but the other U-5-class boats both suffered from inadequate ventilation, which resulted in frequent intoxication of the crew from the engine exhaust. SS-3's underwater propulsion was by two electric motors that totaled 230 shp.

Career
After SS-3's March 1911 launch, Whitehead tried to sell SS-3 to the Austro-Hungarian Navy, but because the evaluation of the first two U-5-class boats was still underway, they declined to purchase. Over the next three years Whitehead attempted to sell the boat to the navies of Peru, Portugal, the Netherlands, Brazil, and Bulgaria, before the Austro-Hungarian Navy rejected an offer for the second time. With the outbreak of war, however, the Austro-Hungarian Navy purchased the unsold submarine to quickly bolster its fleet. Although provisionally assigned the designation U-7, the submarine was commissioned as SM U-12 on 21 August 1914, with Linienschiffsleutnant Egon Lerch in command. U-12's activities over the early part of the war are not reported, but the boat's armament was augmented by a 3.7 cm/23 quick-firing (QF) deck gun in November 1914. Sister boat U-5 had her first radio receiver installed at the same time her deck gun was added, but it is not reported whether U-12 did as well.

On 21 December 1914, Lerch and U-12 chanced upon the French dreadnought FRENCH BATTLESHIP Jean Bart in the Straits of Otranto steaming at a leisurely 9 knots and unprotected by escort ships. U-12 hit French Admiral Lapeyrère's flagship with a single torpedo in the bow, destroying the battleship's wine storeroom but sparing her forward magazine. Jean Bart's watertight compartments saved the ship, which made her way to Malta to undergo repairs at the British dockyards there.

U-12 survived an attack from an unknown French Brumaire-class submarine on 27 February 1915. U-12's next success was the capture of two Montenegrin schooners on 22 March 1916, Fiore Di Dulcigno and Hilussie. Nine days later the U-boat captured another four Montenegrin boats, Buona Forte, Fiore I, Hailie, and Indaverdi. On 29 May, she sank the Greek steamer Virginia, which was the only ship reported sunk by U-12. In June, U-12 underwent a refit that added an additional two torpedo tubes on her forward casing.

In early August, Lerch and U-12 set out from Pola for Venice to look for enemy ships to sink. On 6 August, the Italian destroyer ITALIAN DESTROYER Rosolino Pilo rammed U-12, probably by chance, at about 05:00 in the Lido inlet of the Venetian Lagoon. Two days later, when Italian workers were dredging to try to determine the object Rosolino Pilo had hit, they heard a heavy explosion. When divers went down in the area, they discovered the wreck of U-12 with her stern blown off. U-12's entire complement of 17 men was lost when she went down. U-12 was the first Austro-Hungarian submarine sunk during the war.

In late 1916, the Italians salvaged the hulk of U-12 and transported it to Venice. The bodies of U-12s crew were interred at the San Michele cemetery in Venice, and U-12s hulk, of no salvage value, was scrapped at the Venice naval arsenal. In her military service, U-12 sank one ship of, damaged one warship (22,189 tons), and captured six ships as prizes.