▁area , ▁followed ▁by ▁over ha ul ▁at ▁the ▁Mare ▁Island ▁Navy ▁Y ard ▁in ▁Valle jo , ▁California , ▁from ▁ 1 ▁December ▁ 1 9 3 9 ▁to ▁ 1 ▁March ▁ 1 9 4 0 . ▁ ▁Following ▁her ▁return ▁to ▁San ▁Diego , ▁Sn apper ▁was ▁assigned ▁to ▁Sub R on ▁ 6 ▁and ▁got ▁under way ▁for ▁Hawai i ▁on ▁ 1 ▁April , ▁arriv ing ▁at ▁Pear l ▁Har bor ▁on ▁ 9 ▁April . ▁Ex cept ▁for ▁a ▁brief ▁voyage ▁to ▁San ▁Diego ▁in ▁October ▁and ▁November ▁ 1 9 4 0 , ▁Sn apper ▁remained ▁in ▁the ▁Hawai ian ▁area ▁particip ating ▁in ▁training ▁exer cis es ▁and ▁fleet ▁tact ics ▁until ▁ 3 ▁May ▁ 1 9 4 1 , ▁when ▁she ▁depart ed ▁for ▁over ha ul ▁at ▁the ▁Mare ▁Island ▁Navy ▁Y ard . ▁Upon ▁completion , ▁she ▁became ▁a ▁unit ▁of ▁Sub R on ▁ 2 ▁based ▁at ▁San ▁Diego . ▁During ▁the ▁Japanese ▁attack ▁on ▁Pear l ▁Har bor , ▁Sn apper ▁was ▁operating ▁in ▁the ▁Philipp ine ▁Islands ▁area . ▁ ▁First ▁and ▁second ▁war ▁pat rol s ▁ ▁On ▁ 1 9 ▁December , ▁Sn apper ▁depart ed ▁Man ila ▁for ▁her ▁first ▁war ▁pat rol , ▁covering ▁the ▁sh ipping ▁lan es ▁between ▁Hong ▁Kong ▁and ▁H ain an ▁Stra it ▁until ▁ 8 ▁January ▁ 1 9 4 2 , ▁when ▁she ▁set ▁sail ▁for ▁D ava o ▁G ulf ▁in ▁the ▁Philippines . ▁On ▁