. ▁When ▁it ▁returned ▁to ▁per is cope ▁depth , ▁the ▁m idget ▁found ▁itself ▁west ▁of ▁Fort ▁Den ison . ▁It ▁turned ▁and ▁sa iled ▁east ▁for ▁about ▁, ▁then ▁took ▁up ▁a ▁firing ▁position ▁south - west ▁of ▁Brad ley ' s ▁Head , ▁from ▁where ▁its ▁commander ▁could ▁see ▁Ch ic ag os ▁stern ▁sil hou ett ed ▁against ▁the ▁construction ▁flo od light s ▁at ▁Garden ▁Island ' s ▁new ▁Captain ▁Cook ▁Gra ving ▁D ock . ▁ ▁M idget ▁sub marine ▁M - 2 1 — from ▁I - 2 2 — pro bably ▁entered ▁the ▁har bour ▁at ▁the ▁same ▁time ▁that ▁USS ▁Chicago ▁opened ▁fire ▁on ▁M - 2 4 . ▁The ▁un ar med ▁auxili ary ▁pat rol ▁boat ▁H MA S ▁Laur iana ▁sp otted ▁M - 2 1 ▁and ▁ill umin ated ▁the ▁sub marine ' s ▁con ning ▁tower , ▁while ▁sending ▁an ▁alert ▁signal ▁to ▁the ▁Port ▁War ▁Sign al ▁Station ▁at ▁South ▁Head , ▁and ▁the ▁nearby ▁anti - sub marine ▁vessel ▁H MA S ▁Y andra . ▁Y andra ▁attempted ▁to ▁ram ▁the ▁sub marine , ▁lost ▁contact , ▁reg ained ▁contact ▁at ▁ 2 3 : 0 3 , ▁and ▁dropped ▁six ▁depth ▁charges . ▁At ▁the ▁time ▁of ▁the ▁attack , ▁it ▁was ▁assumed ▁that ▁the ▁depth ▁charges ▁had ▁destroyed ▁or ▁disabled ▁the ▁m idget , ▁but ▁M - 2 1 ▁surv ived . ▁Histor ians ▁believe ▁that ▁the ▁m idget ▁took ▁refuge ▁on ▁the ▁har bour