▁ 2 2 : 3 5 , ▁while ▁Y ar rom a ▁was ▁waiting ▁for ▁permission ▁to ▁fire , ▁and ▁L ol ita ▁was ▁setting ▁up ▁to ▁deploy ▁a ▁third ▁depth ▁charge , ▁the ▁two ▁crew men ▁on ▁M - 1 4 ▁activ ated ▁one ▁of ▁the ▁sub marine ' s ▁sc utt ling ▁charges , ▁killing ▁themselves ▁and ▁destroy ing ▁the ▁sub marine ' s ▁forward ▁section . ▁ ▁Mu ir head - G ould ▁gave ▁the ▁general ▁alarm , ▁along ▁with ▁orders ▁for ▁ships ▁to ▁take ▁anti - sub marine ▁measures , ▁at ▁ 2 2 : 2 7 ; ▁the ▁alarm ▁was ▁repeated ▁at ▁ 2 2 : 3 6 ▁with ▁advice ▁for ▁ships ▁to ▁take ▁pre ca utions ▁against ▁attack , ▁as ▁an ▁enemy ▁sub marine ▁might ▁be ▁in ▁the ▁har bour . ▁At ▁the ▁time ▁of ▁the ▁first ▁alarm , ▁Sydney ▁Har bour ▁was ▁closed ▁to ▁external ▁traffic , ▁but ▁Mu ir head - G ould ▁ordered ▁fer ries ▁and ▁other ▁internal ▁traffic ▁to ▁continue , ▁as ▁he ▁believed ▁that ▁having ▁multiple ▁ships ▁trav elling ▁around ▁at ▁speed ▁would ▁help ▁force ▁any ▁sub mar ines ▁to ▁remain ▁sub mer ged . ▁ ▁M idget ▁sub marine ▁M - 2 4 ▁was ▁the ▁second ▁to ▁enter ▁the ▁har bour . ▁H MA S ▁Fal ie ▁gra zed ▁M - 2 4 s ▁h ull ▁and ▁reported ▁the ▁contact ▁to ▁command . ▁The ▁report ▁was ▁not ▁followed ▁up . ▁M - 2 4 ▁crossed ▁the ▁indicator ▁loop ▁und et ected