ped o - rid ers ▁were ▁also ▁captured , ▁but ▁their ▁mines ▁s ank ▁V ali ant , ▁the ▁batt les hip ▁, ▁and ▁the ▁Norwegian ▁tank er ▁S ag ona , ▁and ▁badly ▁dam aged ▁the ▁destroy er ▁. ▁The ▁two ▁batt les hips ▁s ank ▁in ▁only ▁a ▁few ▁feet ▁of ▁water ▁and ▁were ▁subsequently ▁re - f lo ated . ▁Nevertheless , ▁they ▁were ▁out ▁of ▁action ▁for ▁over ▁a ▁year . ▁▁ 1 9 4 2 ▁▁ ▁April ▁ 2 9 , ▁ 1 9 4 2 : ▁The ▁Italian ▁sub marine ▁Am bra ▁depart ed ▁La ▁Spe zia ▁carrying ▁three ▁man ned ▁tor ped o es . ▁At ▁L eros ▁six ▁crew men ▁were ▁secret ly ▁loaded ▁for ▁them . ▁On ▁May ▁ 1 4 ▁Am bra ▁reached ▁Alexand ria ▁and ▁s ank ▁a ▁British ▁floating ▁dock . ▁ ▁The ▁Am bra ▁was ▁sp otted ▁and ▁could ▁not ▁sink ▁anything . ▁All ▁six ▁tor ped o - rid ers ▁were ▁captured . ▁ ▁July ▁ 1 9 4 2 : ▁Italian ▁f rog men ▁set ▁up ▁in ▁a ▁secret ▁base ▁in ▁the ▁Italian ▁tank er ▁Ol terra ▁which ▁was ▁intern ed ▁in ▁Al ge cir as ▁near ▁Gib ral tar . ▁All ▁materials ▁had ▁to ▁be ▁moved ▁secret ly ▁through ▁Spain ▁and ▁this ▁limited ▁operations . ▁ ▁July ▁ 1 3 , ▁ 1 9 4 2 : ▁Tw elve ▁Italian ▁f rog men ▁sw am ▁from ▁the ▁Al ge cir as ▁coast ▁into ▁Gib ral tar ▁har