 The German submarines in the Black Sea accomplished little , sinking only six ships between August 1916 and the end of the year . UB @-@ 42 sank half of the six in September and October . On 3 September , Wernicke and UB @-@ 42 achieved their first success when they sank the Russian transport Peter Darcy in the Black Sea . The 731 @-@ ton ship was headed from <unk> to Odessa when torpedoed by UB @-@ 42 . The 150 @-@ ton Russian vessel St. <unk> was sunk at the entrance to <unk> Bay on 5 October , and the 2 @,@ 891 @-@ ton <unk> was sunk two weeks later off Cape <unk> . 
