HM Armed Smack Inverlyon His Majesty ' s or HM Armed Smack " Inverlyon " was a fishing smack that was converted to a Q - ship during the First World War . Q - ships served as decoys to lure German submarines near enough so that concealed weapons could be brought to bear and sink the submarines . On 15 August 1915 , " Inverlyon " succeeded in luring German submarine within range and sinking her with nine shots from her gun . The Royal Navy in command of the vessel , Ernest Martin Jehan , received the Distinguished Service Cross and members of " Inverlyon " s crew shared the bounty offered for German submarines . After " Inverlyon " s Q - ship career ended , she returned to fishing , but was sunk by on 1 February 1917 . Career . " Inverlyon " was a fishing smack of 59 tons burthen that was a part of the fishing fleet at Lowestoft on the Suffolk coast . The wooden boat had a flush deck , two mast s , and no engine . " Inverlyon " s sails were fore - and - aft rig ged and may have been red ochre in colour , the traditional sail colour for British smacks . In February 1915 , Germany began its first submarine offensive of the First World War . During this campaign , enemy vessels in the German - defined war zone ( ) , which encompassed all waters around the United Kingdom , were to be sunk , and the British fishing fleet was not exempt . In mid - June , for example , the German submarine had sunk six smacks off Lowestoft in a two - day period . One method devised to deal with U - boat attacks was the decoy or Q - ship , designed to lure submarines that were targeting merchant shipping close enough so that concealed guns or other weapons could sink them . " Inverlyon " was selected to become a Q - ship , was outfitted with either a 3 - pounder ( 47 mm ) or a 6 - pounder ( 57 mm ) gun , and entered the service of the Royal Navy on 2 August 1915 . " Inverlyon " s fishing crew and skipper were all temporarily inducted into the Trawler section of the Royal Naval Reserve . Regular Royal Navy Ernest Martin Jehan and three other gunners from — a former torpedo boat operating as a minesweeper out of Lowestoft — were assigned to " Inverlyon " , with Jehan in command . On 14 August , the 59 - ton smack " Bona Fide " was stopped by a U - boat , boarded , and sunk with explosives east - northeast from Lowestoft . This attack was likely by " UB - 4 " , because she was operating in that 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 . Unbeknown to " UB - 4 " s commander , " Oberleutnant zur See " Karl Gross , one of the fishing vessels was the disguised " Inverlyon " . Around 20 : 20 , " UB - 4 " surfaced near " Inverlyon " , and Gross , on the conning tower of " UB - 4 " , began shouting out commands to " Inverlyon " s crew in German . Jehan , after waiting until " UB - 4 " closed to within of " Inverlyon " , ordered the White Ensign raised and gave the command to open fire . A burst of three rounds from the " Inverlyon " s weapon scored hits on the conning tower , the second shot 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 , " Inverlyon " s gunner unleashed 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 . " Inverlyon " s fishing skipper , a man named Phillips , dived in to attempt the rescue of a crewman from " UB - 4 " . Phillips was unable to reach him before the crewman went under and met same fate as Gross and " UB - 4 " s twelve other crewmen . As " UB - 4 " went down she fouled " 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 . This was 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 . On 19 November 1915 Jehan was awarded the Distinguished Service Cross ( DSC ) for the sinking of " UB - 4 " , and the crewmen of " Inverlyon " split the submarine bounty paid by the Admiralty . About three weeks after she sank " UB - 4 " , " Inverlyon " had the opportunity to sink another U - boat , but was unsuccessful . The U - boat encountered may have been either or , which both sank fishing vessels in the area on 7 and 8 September . By 1916 , " Inverlyon " had ended her short - lived Q - ship career and returned to being a fishing boat . Jehan , in addition to his DSC , was subsequently specially promoted to lieutenant on 4 January 1916 for his war service ; he retired from the Royal Navy on 29 October 1920 . On 1 February 1917 , the German submarine shelled and sank " Inverlyon " from Trevose Head at position ; there were no reported casualties .