▁fourth ▁war ▁pat rol . ▁On ▁ 1 9 ▁August , ▁she ▁fired ▁two ▁tor ped o es ▁at ▁a ▁cargo ▁ship ▁but ▁lost ▁contact ▁when ▁forced ▁to ▁e va de ▁an ▁esc ort ▁ship . ▁The ▁only ▁other ▁targets ▁sight ed ▁during ▁this ▁pat rol ▁were ▁at ▁too ▁great ▁a ▁distance ▁or ▁on ▁a ▁course ▁and ▁speed ▁that ▁prevent ed ▁the ▁sub marine ▁from ▁closing . ▁ ▁Fif th , ▁sixth ▁and ▁sevent h ▁war ▁pat rol s ▁ ▁Although ▁both ▁the ▁fifth ▁and ▁sixth ▁war ▁pat rol s ▁were ▁also ▁un product ive , ▁during ▁the ▁sevent h , ▁conducted ▁in ▁the ▁vic inity ▁of ▁Gu am , ▁Sn apper ▁s ank ▁her ▁initial ▁victim ▁of ▁the ▁war . ▁According ▁to ▁her ▁war ▁di ary , ▁she ▁sight ed ▁two ▁vessels ▁mo ored ▁in ▁the ▁extreme ▁n ortheast ▁corner ▁of ▁Ap ra ▁Har bor , ▁Gu am , ▁and ▁decided ▁to ▁pat rol ▁sub mer ged ▁off ▁the ▁har bor ▁until ▁they ▁depart ed . ▁Seven ▁days ▁later , ▁on ▁ 2 7 ▁August , ▁she ▁head ed ▁to ▁the ▁north ▁of ▁the ▁har bor , ▁firing ▁three ▁tor ped o es ▁at ▁the ▁first ▁target ▁and ▁one ▁at ▁the ▁second . ▁As ▁she ▁quickly ▁depart ed ▁the ▁vic inity , ▁Sn apper ▁observed ▁one ▁hit ▁on ▁the ▁first ▁target , ▁s inking ▁the ▁passenger - c argo ▁ship ▁Tok ai ▁Mar u , ▁stern ▁first . ▁ ▁On ▁ 2 ▁September , ▁Sn apper ▁closed ▁a ▁con voy ▁of ▁five