 On 14 May , Wernicke was succeeded by Kapitänleutnant Kurt Schwarz as commander of UB @-@ 42 . The 27 @-@ year @-@ old Schwarz , who had previously commanded the Type UB I boat UB @-@ 14 , led UB @-@ 42 to sink her largest ship , <unk> , on 24 June . The 8 @,@ 912 @-@ ton former Leyland Line steamer was in use as a troopship , carrying 800 troops and horses when Schwarz sent her down 4 nautical miles ( 7 @.@ 4 km ; 4 @.@ 6 mi ) southeast of Skyros in the Aegean . Three of <unk> 's crewmen died in the attack and , according to R. H. Gibson and Maurice Prendergast , " splendid discipline " among the embarked troops was the sole reason that none were lost . 
