SM UB - 4 Seiner Majestät " UB - 4 " was a German Type UB I submarine ( U - boat ) in the German Imperial Navy ( ) during World War I . She was sunk by a British Q - ship disguised as a fishing smack in August 1915 . " UB - 4 " was ordered in October 1914 and was laid down at the Germaniawerft shipyard in Kiel in November . " UB - 4 " was a little more than in length and displaced between , depending on whether surfaced or submerged . She carried two torpedo es for her two bow torpedo tube s and was also armed with a deck - mounted machine gun . " UB - 4 " was broken into sections and shipped by rail to Antwerp for reassembly . She was launched and commissioned as SM " UB - 4 " in March 1915 . " UB - 4 " conducted the first sortie of the Flanders Flotilla in April , during which she sank the Belgian Relief ship , the first ship credited to the flotilla . She sank three more ships from mid - April to mid - August . On 15 August , " UB - 4 " surfaced near the British Q - ship and was sunk by gunfire from the sailing vessel . None of " UB - 4 " s 14 crewmen survived the attack . Design and construction . After the German Army ' s rapid advance along the North Sea coast in the earliest stages of World War I , the German Imperial Navy found itself without suitable submarines that could be operated in the narrow and shallow environment off Flanders . Project 34 , a design effort begun in mid - August 1914 , produced the Type UB I design : a small submarine that could be shipped by rail to a port of operations and quickly assembled . Constrained by railroad size limitations , the UB I design called for a boat about long and displacing about with two torpedo tube s . " UB - 4 " was part of the initial allotment of eight submarines — numbered to — ordered on 15 October from Germaniawerft of Kiel , just shy of two months after planning for the class began . " UB - 4 " was laid down by Germaniawerft in Kiel on 3 November . As built , " UB - 4 " was long , abeam , and had a draft of . She had a single Daimler 4 - cylinder diesel engine for surface travel , and a single Siemens - Schuckert electric motor for underwater travel , both attached to a single propeller shaft . Her top speeds were , surfaced , and , submerged . At more moderate speeds , she could sail up to on the surface before refueling , and up to submerged before recharging her batteries . Like all boats of the class , " UB - 4 " was rated to a diving depth of , and could completely submerge in 33 seconds . " UB - 4 " was armed with two torpedo es in two bow torpedo tube s . She was also outfitted for a single machine gun on deck . " UB - 4 " s standard complement consisted of one officer and thirteen enlisted men . After work on " UB - 4 " was complete at the Germaniwerft yard , " UB - 4 " was readied for rail shipment . The process of shipping a UB I boat involved breaking the submarine down into what was essentially a knock down kit . Each boat was broken into approximately fifteen pieces and loaded on to eight railway flatcar s . In early 1915 , the sections of " UB - 4 " were shipped to Antwerp for assembly in what was typically a two - to three - week process . After " UB - 4 " was assembled and launched sometime in March , she was loaded on a barge and taken through canals to Bruges where she underwent trials . Service career . The submarine was commissioned into the German Imperial Navy as SM " UB - 4 " on 23 March under the command of " Oberleutnant zur See " Karl Gross , a 29 - year - old first - time U - boat commander . " UB - 4 " soon joined the other UB I boats then comprising the Flanders Flotilla ( ) , which had been organized on 29 March . When " UB - 4 " joined the flotilla , Germany was in the midst of its first submarine offensive , begun in February . During this campaign , enemy vessels in the German - defined war zone ( ) , which encompassed all waters around the United Kingdom ( including the English Channel ) , were to be sunk . Vessels of neutral countries were not to be attacked unless they definitively could be identified as enemy vessels operating under a false flag . " UB - 4 " kicked off operations for the new flotilla when she departed on her first patrol on 9 April . The following day , she sank the first ship credited to the Flanders Flotilla . The 5 , 940 - ton British - flagged , which had been chartered by the American Commission for Relief in Belgium , was headed for Norfolk , Virginia , United States , in ballast after delivering relief supplies to Rotterdam . " UB - 4 " came upon the steamer between Harwich and the Hook of Holland and pulled to within about . Despite the fact that the ship had a pass of safe - conduct from Germany , was marked with the words " Belgian Relief " on her side , and was flying a white flag with the same wording , Gross torpedoed the vessel without warning . " Harpalyce " sank in about five minutes , which allowed no time to launch any of the lifeboat s . The Dutch steamers " Elisabeth " and " Constance " , and the American steamer " Ruby " picked up survivors . Herbert Hoover , head of the relief committee , reported that his organization ' s charter of the ship ended after delivery of the cargo in Rotterdam , but expressed disbelief that the ship could have been the victim of a torpedo attack , given the " distinct assurance " that ships engaged in the relief effort " would not be molested " . " Harpalyce " s master and 14 others from the 44 - man crew died in the attack . " Harpalyce " was the largest ship sunk by " UB - 4 " during her career . " UB - 4 " s followed up the sinking of " Harpalyce " by sinking the Greek ship " Ellispontos " , a steamer of . " Ellispontos " was en route to Montevideo from Amsterdam when sunk by Gross and " UB - 4 " on 17 April . Although German U - boats sank over 100 , 000 tons of shipping in each of May and June , " UB - 4 " did not contribute to those totals . She did add one ship to the 98 , 000 - ton tally for July when she sank the Belgian ship " Princesse Marie Jose " and her load of coal on 29 July . The 1 , 954 - ton steamer had sailed from Dunston and was headed to Bordeaux when sunk from the Shipwash Lightship off Harwich . Sinking . On 14 August , the 59 - ton British fishing smack " Bona Fide " was stopped by a U - boat , boarded , and sunk with explosives east - northeast of Lowestoft . According to the website Uboat . net , this attack was likely by " UB - 4 " , because she was operating in the area on her fourteenth patrol . Regardless of the identity of " Bona Fide " s attacker , " UB - 4 " did approach a group of smacks in the vicinity the next day , but unbeknownst to " UB - 4 " s commander , Gross , one of the fishing vessels was actually a British decoy ship . The decoy or Q - ship was His Majesty ' s Armed Smack , a smack that had been outfitted with a concealed 3 - pounder ( 47 mm ) gun . Around 20 : 20 , " UB - 4 " drew within of " Inverlyon " and Gross , on the conning tower of " UB - 4 " , shouted out commands to " Inverlyon " s crew in German . After waiting until the right moment , Ernest Jehan , a Royal Navy gunner in command of " Inverlyon " , ordered the White Ensign raised and gave the command to open fire . A burst of three rounds from the 3 - pounder scored hits on the conning tower , the second destroying part of the bridge and sending Gross into the water . " UB - 4 " , with no one at the helm , drifted behind " Inverlyon " , and when clear , the 3 - pounder fired another six shots into the hull of " UB - 4 " at point blank range . All the while small arms fire from " Inverlyon " s crew peppered the submarine . The U - boat began going down by the bow , becoming nearly vertical before disappearing below the surface . A member of " Inverlyon " s crew attempted the rescue of one crewman from " UB - 4 " , but was unable to reach him before he went under , meeting the same fate as the other thirteen crewmen . As " UB - 4 " went down , her hulk fouled the " Inverlyon " s nets — which had been deployed to keep up the appearance of a real fishing boat — essentially anchoring " Inverlyon " in place . The Q - ship ' s crew , not having a wireless set on board , sent word of the encounter with another smack , and followed up by releasing messenger pigeon s the following morning , requesting instructions on what to do with " UB - 4 " . The thought of salvaging the snagged U - boat was rejected , so the nets were cut , freeing " UB - 4 " to sink to the bottom . " UB - 4 " s wreck lies at position . Jehan was awarded the Distinguished Service Cross for the sinking of " UB - 4 " , and the crewmen of " Inverlyon " split the submarine bounty paid by the Admiralty .