SM UB - 50 SM " UB - 50 " was a German Type UB III submarine or U - boat in the German Imperial Navy ( ) during World War I . The U - boat was ordered on 20 May 1916 . She was commissioned into the Pola Flotilla of the German Imperial Navy on 12 July 1917 as SM " UB - 50 " . The submarine conducted seven patrols and sank 38 ships during the war for a total loss of . She operated as part of the Pola Flotilla based in Cattaro . " UB - 50 " surrendered on 16 January 1919 with the remainder of the Pola Flotilla following an order by Admiral Reinhard Scheer to return to port . During her passage through the Straits of Gibraltar , she managed to sink the battleship . " UB - 50 " was later broken up at Swansea . Construction . " UB - 50 " was ordered by the German Imperial Navy on 20 May 1916 . She was built by Blohm & Voss , Hamburg and following just under a year of construction , launched at Hamburg on 6 January 1917 . " UB - 50 " was commissioned later that same year under the command of " Kapitänleutnant " ( Kptlt . ) Franz Becker . Like all Type UB III submarines , " UB - 50 " carried 10 torpedoes and was armed with an deck gun . " UB - 50 " could carry a crew of up to 34 men and had a cruising range of . " UB - 50 " had a displacement of while surfaced and when submerged . Her engines enabled her to travel at when surfaced and when submerged . Service history . First patrol . Soon after she left Pola , " UB - 50 " encountered the " William H . Crawford " , a American sailing ship . It sank after an attack from the U - boat stopped her . Four days later , " UB - 50 " sighted the British barge " R . B . 40 " . " UB 50 " launched a torpedo which instead hit the British tug towing the ship , the " H . s . 3 " . The tug sank , but the barge was not sunk . The following day , " UB - 50 " found two Portuguese sailboats " Correiro De Sines " and " Comizianes Da Graca " at and respectively . They were sunk north of Cape Sines . A day later , she found the Portuguese ship " Sado " , which she sank about south of her prey the day before . Four days later , " UB - 50 " finally encountered and sank a merchant , this being the British " Polar Prince " , carrying coal for Malta . Two days later , she sank the " Fabian " , a British steamer going to Liverpool , killing three . Later that day , she sank the " Gioffredo Mameli " , a ton Italian steamer carrying ore . The coal carrying Greek steamer " Alkyon " was attacked two days later by " UB - 50 " , sinking close off Oran . The UB 50 followed up with the sinking of the Norwegian steamer " John Knudsen " , killing one . Four days later , the Italian sailboat " Ciro " was scuttled after being hit by " UB - 50 " , the last ship she would sink before returning to base . Second patrol . SM " UB - 50 " began her second patrol with the sinking of the " Marc Fraissinet " , a French steamer carrying wood , munitions , and hay to Bizerte . It sank north of Tabarca after being torpedoed by " UB - 50 " . Later that day UB 50 encountered the " Senegal " , an Italian steamer , sinking her off the coast of Algeria with no casualties . Three days after that , the " Margram Abbey " , a British steamer carrying coal , was found and torpedoed by " UB - 50 " . It was beached off of the coast of Algeria , but the torpedo damage , which killed two , had wrecked the ship . UB 50 attacked the " Antaeus " , a British steamer , three days later off of Cape Bon . There were no casualties , but the captain was taken prisoner . On the following day , UB 50 torpedoed the " Amberton " , a British steamer , but she was only damaged . Four days later , the submarine found her last target of her second patrol , the American steamer " Rizal " , which sank from Cape Cavallo . Third patrol . " UB - 50 " started out her third patrol by finding and sinking the Italian sailboat " S . Giuseppe B . " off the coast of Africa . She sank the British steamer " City of Lucknow " two days later northeast of the Cani Rocks . On Christmas Day , 1917 , " UB - 50 " sank the " Sant ’ Antonio " , an Italian sailing vessel , by gunfire near Bizerte . On New Year ' s Day , 1918 , the " Egyptian Transport " , a British steamer , was damaged during an attack by " UB - 50 " , which killed five men . It was later beached but refloated . Two days later , the " Allanton " , a British steamer carrying coal , was sunk by UB - 50 , which also sunk the " Steelville " , a British steamer also carrying coal later that day . Four days later , " UB - 50 " torpedoed the " Arab " , a British steamer coal off the coast of Cape Serrat , killing 21 . Fourth patrol . " UB - 50 " s fourth patrol was very successful . In less than a month , she sank six vessels . The first victim was the French steamer " Saint Jean Ii " , which went down 22 March 1918 off of Cap Bon . That same day , " UB - 50 " managed to damage the British steamer " Shadwell " off of Bizerta . Four days later " UB - 50 " sank the Italian steamer " Volturno " off of Bone ( Annaba ) , Algeria . On 6 April , " UB - 50 " sank the French vessel " Madeleine Iii " and on 11 April , she sank the Italian sailing ship " Carmela G " and the British vessel " Highland Prince " . Fifth patrol . " UB - 50 " began her fifth war patrol by damaging the British steamer " Elswick Grange " carrying coal off of the coast of Oran , killing one . Two days later , she ran across the British steamer " Mavisbrook " carrying coal . She was torpedoed south east of Cabo de Gata , killing 18 . On that same day , she came upon the Danish three - masted iron - hulled schooner " Kirstine Jesen " , sinking after being fired upon from " UB - 50 " < nowiki > ' < / nowiki > s deck gun with no deaths . Two days later , the " New Sweden " , a Swedish steamer , was hit by " UB - 50 " and sank . Two days later , " UB - 50 " found the Spanish steamer " Maria Pia " , which sank with no casualties . Three days after that , the French sailboat " Animal Lafont " and Italian sailboat " Santa Teresa " were torpedoed by the U - boat with no casualties . Sixth patrol . Shortly before her sixth patrol , " Oberleutnant zur See " Heinrich Kukat took over command from Kptlt . Becker . On her sixth patrol , " UB - 50 " encountered the " Imber " , a British steamer and torpedoed her south of Cape St . Maria di Leuca , though she survived . Three days later , " UB - 50 " sank the " War Swallow " , a British merchant ship carrying coal from the River Tyne to Port Said . Another three days passed before " UB - 50 " found her next target , the Italian steamer " Adria 1 " , a ship carrying cotton from Palermo to Tunis . It sank , but no lives were lost . Two days later , the British steamer " Upada " was torpedoed by " UB - 50 " killing three , but was only damaged . " UB - 50 " sank the " Messidor " , a British coal steamer two days later , sinking the ship and killing one . The following day , she torpedoed the " Rutherglen " , a British steam merchant carrying coal . That was followed by an attack on the " Magellan " , a British steamer on the following day . She sank with one man . The last ship sunk on the patrol was the " Antonio S . " , a Italian sailboat sunk off of the coast of Tunisia . Seventh patrol . On 9 November 1918 , two days before the Armistice with Germany , " UB - 50 " sank the British battleship HMS " Britannia " . The " Britannia " was on a voyage to Gibraltar when she was torpedoed off Cape Trafalgar . After the initial explosion , the ship began listing ten degrees to port . A few minutes later , another explosion started a fire in a magazine , which resulted in a cordite explosion in the magazine . The " Britannia " stayed at 10 - degrees for 2½ hours before sinking . Its 16 , 350 gross register tons made it the largest ship the U - boat ever sank , and the only one " UB - 50 " would sink during her last patrol .