SM U-28 (Austria-Hungary)

SM U-28 or U-XXVIII was a U-27-class submarine U-boat or submarine for the Austro-Hungarian Navy. U-28, built by the Austrian firm of Cantiere Navale Triestino (CNT) at the Pola Navy Yard, was launched in January 1917 and commissioned in June.

She had a single hull and was just over 121 ft in length. She displaced nearly 265 MT when surfaced and over 300 MT when submerged. Her two diesel engines moved her at up to 9 knots on the surface, while her twin electric motors propelled her at up to 7.5 knots while underwater. She was armed with two bow torpedo tubes and could carry a load of up to four torpedoes. She was also equipped with a 75 mm deck gun and a machine gun.

During her service career, U-28 sank the British Q-ship HMS SS Bradford City and nine other ships, sending a combined tonnage of 44,743 to the bottom. U-28 was surrendered at Venice in 1919, granted to Italy as a war reparation and broken up the following year.

Design and construction
Austria-Hungary's U-boat fleet was largely obsolete at the outbreak of World War I. The Austro-Hungarian Navy satisfied its most urgent needs by purchasing five Type UB I submarines that comprised the U-10-class submarine from Germany, by raising and recommissioning the sunken French submarine FRENCH SUBMARINE Curie as SMU U-14 (Austria-Hungary), and by building four submarines of the U-20-class submarine that were based on the 1911 Danish Havmanden-class submarine.

After these steps alleviated their most urgent needs, the Austro-Hungarian Navy selected the German Type UB II design for its newest submarines in mid 1915. The Germans were reluctant to allocate any of their wartime resources to Austro-Hungarian construction, but were willing to sell plans for up to six of the UB II boats to be constructed under license in Austria-Hungary. The Navy agreed to the proposal and purchased the plans from AG Weser of Bremen.

U-28 displaced 264 MT surfaced and 301 MT submerged. She had a single hull with saddle tanks, and was 121 ft long with a beam of 14 ft and a draft of 12 ft. For propulsion, she had two shafts, twin diesel engines of 270 bhp for surface running, and twin electric motors of 280 shp for submerged travel. She was capable of 9 knots while surfaced and 7.5 knots while submerged. Although there is no specific notation of a range for U-28 in Conway's All the World's Fighting Ships 1906–1921, the German UB II boats, upon which the U-27 class was based, had a range of over 6000 nmi at 5 knots surfaced, and 45 nmi at 4 knots submerged. U-27-class boats were designed for a crew of 23–24.

U-28 was armed with two 45 cm bow torpedo tubes and could carry a complement of four torpedoes. She was also equipped with a 75 mm/26 caliber deck gun and an 8 mm machine gun.

After intricate political negotiations to allocate production of the class between Austrian and Hungarian firms, U-28 was ordered from Cantiere Navale Triestino (CNT) on 12 October 1915. She was laid down by early 1916 at the Pola Navy Yard, and launched on 8 January 1917.

Service career
After her completion, U-28 was commissioned into the Austro-Hungarian Navy on 26 June 1917 under the command of Linienschiffsleutnant Zdenko Hudeček. Previously in command of SMU U-17 (Austria-Hungary), Hudeček was a 30-year-old native of Theresienstadt (present-day Terezín in the Czech Republic). Four days after the U-boat's commissioning, Hudeček achieved his first kill at the helm of U-28. On 30 June, while on patrol about 40 nmi east of Malta, U-28 came upon the 4,809 GRT British steamer Haigh Hall. The turret hull ship was carrying wheat from Bombay to Naples when torpedoed and sunk by Hudeček. Three days later, the British India passenger ship SS Mongara met the same fate. Even though escorted by an Italian destroyer and a trawler, Mongara was torpedoed and sunk by U-28 just 1.5 nmi from the breakwater at Messina. The 8,205 GRT liner—the largest ship sunk by U-28 —was en route from Sydney to London when she went down, but was spared any loss of life in the attack. In eight days in commission, U-28's tally was over 13,000 GRT, already exceeding the totals of all four U-boats of the U-20-class submarine.

The following month, U-28 sank the 3,881 GRT collier Maston 35 nmi from Cape Spartivento, Calabria, on 13 August, killing two men of the British ship's crew. Three days after Maston went down, U-28 sank HMS Bradford City, a 3,683 GRT British Q ship in the Straits of Messina, with no loss of life. HMS Bradford City, operating under the pseudonym Saros, had been particularly detached to the Straits to hunt U-28 and had ignored orders to proceed to port from officers unaware of her naval status. After the torpedo struck, the ship's "panic party" had taken to the boats in the hope of luring her attacker to the surface, but the arrival of the French naval trawler Hiver drove U-28 away before the gun crews aboard HMS Bradford City could engage the submarine. HMS Bradford City sank within 30 minutes off San Remo. In October, U-28 closed out her 1917 list of victims with Bontnewydd, a British steamer sunk 60 nmi north-northeast of Susa. The 3,296 GRT steamer was sailing in ballast from Marseilles for Karachi.

In January 1918, U-28 sank an additional three ships. Bosforo, an Italian steamer of 2,723 GRT headed for Salonika, was sent to the bottom near Cape Spartivento on 12 January. The following day, U-28 dispatched the British steamer Rapallo 1.5 nmi south of Cape Peloro. One sailor aboard the one-year-old ship died in the attack, which occurred while the ship was headed to Messina in ballast. On 21 January, West Wales, a collier headed from Barry to Alexandria, was sunk 140 nmi from Malta, taking her load of coal and two of her crew to the bottom.

On 8 March, U-28 attacked two ships, sinking one of them. The first ship, Mitra, a 5,592 GRT tanker was hit by U-28 but was able to make port in Malta with her cargo of oil. Later in the month, U-28 sank SS Uganda (1905) 32 nmi from Linosa, killing one sailor in the attack. The 1905 British ship was carrying cotton and cottonseed from Alexandria for London when the attack occurred. Three days later, Stolt Nielsen, a 5,684 GRT steamship, was sent to the bottom 38 nmi from Malta. Carrying a general cargo for the Admiralty when she went down, the British ship turned out to be the final ship to be sunk by U-28.

At the war's end, U-28 was surrendered to Italy at Venice in 1919. Later awarded to Italy as a war reparation, she was scrapped at Venice in 1920. In her 18-month career, U-28 sank ten ships with a combined tonnage of 44,743, and damaged an eleventh.