▁reached ▁Horn s ▁Re ef ▁by ▁ 4 : 0 0 ▁on ▁ 1   J une . ▁At ▁ 0 6 : 2 0 , ▁however , ▁Ost f ries land ▁struck ▁a ▁mine , ▁previously ▁laid ▁by ▁the ▁destroy er ▁ ▁on ▁ 4 ▁May , ▁on ▁her ▁star board ▁side . ▁The ▁ship ▁ha u led ▁out ▁of ▁line , ▁as ▁the ▁explos ion ▁was ▁initially ▁thought ▁to ▁have ▁been ▁a ▁tor ped o ▁fired ▁by ▁a ▁sub marine . ▁Ost f ries land ▁fell ▁behind ▁the ▁fleet ▁and ▁ste amed ▁at ▁slow ▁speed , ▁screen ed ▁by ▁the ▁destroy ers ▁, ▁, ▁and ▁briefly ▁by ▁. ▁By ▁ 1 0 : 4 0 , ▁the ▁batt les hip ▁had ▁increased ▁speed ▁to ▁. ▁Her ▁anti - sub marine ▁esc ort ▁was ▁eventually ▁rein for ced ▁by ▁a ▁float plane , ▁which ▁sp otted ▁what ▁it ▁believed ▁to ▁be ▁a ▁British ▁sub marine ▁at ▁ 1 2 : 2 0 . ▁Ost f ries land ▁turned ▁away , ▁which ▁caused ▁the ▁tor ped o ▁bulk head , ▁dam aged ▁slightly ▁by ▁the ▁mine ▁explos ion , ▁to ▁te ar ▁open . ▁More ▁water ▁entered ▁the ▁ship ▁and ▁caused ▁a ▁ 4 . 7 5   deg ree ▁list ▁to ▁star board , ▁forcing ▁Ost f ries land ▁to ▁reduce ▁speed ▁again . ▁The ▁ship ▁requested ▁assistance ▁from ▁a ▁p ump ing ▁ship ▁at ▁ 1 4 : 2 0 , ▁but ▁by ▁ 1 4 : 4 5 ▁the ▁flo