▁M idget ▁sub marine ▁M - 1 4 — launch ed ▁from ▁I - 2 7 – was ▁the ▁first ▁to ▁enter ▁Sydney ▁Har bour . ▁The ▁Middle ▁Head   – ▁South ▁Head ▁loop ▁detected ▁it ▁at ▁ 2 0 : 0 1 , ▁but ▁dismiss ed ▁the ▁reading ▁due ▁to ▁heavy ▁civil ian ▁traffic . ▁At ▁ 2 0 : 1 5 , ▁a ▁Mar itime ▁Services ▁Board ▁watch man ▁sp otted ▁the ▁m idget ▁after ▁it ▁passed ▁through ▁the ▁western ▁gap , ▁coll ided ▁with ▁the ▁P ile ▁Light , ▁then ▁revers ed ▁and ▁tra pped ▁its ▁stern ▁in ▁the ▁net . ▁The ▁sub marine ' s ▁bow ▁broke ▁the ▁surface ; ▁the ▁watch man ▁row ed ▁toward ▁it ▁to ▁determine ▁what ▁it ▁was ▁and ▁then ▁row ed ▁to ▁the ▁nearby ▁pat rol ▁boat ▁ ▁to ▁report ▁his ▁finding . ▁Despite ▁efforts ▁by ▁Y ar rom a ▁to ▁pass ▁on ▁this ▁information , ▁Sydney ▁Naval ▁Head quarters ▁did ▁not ▁receive ▁the ▁report ▁until ▁ 2 1 : 5 2 . ▁H MA S ▁Y ar rom a ▁and ▁ ▁were ▁dispatch ed ▁to ▁investigate . ▁Upon ▁confirm ing ▁that ▁the ▁object ▁in ▁the ▁net ▁was ▁a ▁" b aby ▁sub marine ", ▁L ol ita ▁dropped ▁two ▁depth ▁charges ▁while ▁Y ar rom as ▁commander ▁requested ▁permission ▁from ▁Sydney ▁Naval ▁Head quarters ▁to ▁open ▁fire . ▁The ▁depth ▁charges ▁failed ▁to ▁det on ate , ▁as ▁the ▁water ▁was ▁too ▁shall ow ▁for ▁the ▁hydro static ▁f use ▁setting . ▁At