bel ief ▁demonstrated ▁in ▁the ▁early ▁hours ▁of ▁the ▁attack . ▁ ▁F la ws ▁in ▁Japanese ▁tact ics ▁ ▁The ▁main ▁f law ▁in ▁the ▁Japanese ▁plans ▁was ▁the ▁use ▁of ▁m idget ▁sub mar ines ▁for ▁the ▁primary ▁attack . ▁M idget ▁sub mar ines ▁were ▁originally ▁intended ▁to ▁operate ▁during ▁fleet ▁actions : ▁they ▁would ▁be ▁released ▁from ▁modified ▁se ap lane ▁carri ers ▁to ▁run ▁am ok ▁through ▁the ▁enemy ▁fleet . ▁This ▁concept ▁went ▁out ▁of ▁favour ▁as ▁changing ▁Japanese ▁naval ▁thinking ▁and ▁experience ▁led ▁to ▁recognition ▁that ▁naval ▁war fare ▁would ▁centre ▁around ▁car rier - supported ▁aer ial ▁combat . ▁As ▁a ▁result , ▁the ▁m idget ▁program ' s ▁focus ▁changed ▁to ▁the ▁in fil tr ation ▁of ▁enemy ▁har b ours , ▁where ▁they ▁would ▁attack ▁vessels ▁at ▁anchor . ▁This ▁concept ▁failed ▁completely ▁during ▁the ▁attack ▁on ▁Pear l ▁Har bor , ▁where ▁the ▁m idget s ▁had ▁no ▁effect , ▁and ▁t ying ▁up ▁ 1 1 ▁large ▁sub mar ines ▁for ▁six ▁weeks ▁in ▁support ▁of ▁further ▁m idget ▁sub marine ▁attacks ▁on ▁Sydney ▁and ▁Diego ▁Su are z ▁proved ▁a ▁waste ▁of ▁resources . ▁ ▁Moreover , ▁the ▁fail ures ▁at ▁Sydney ▁Har bour ▁and ▁Diego ▁Su are z ▁demonstrated ▁that ▁the ▁improvements ▁to ▁the ▁m idget ▁sub mar ines ▁made ▁after ▁Pear l ▁Har bor ▁had ▁not ▁increased ▁the ▁overall ▁impact ▁of ▁the ▁m idget ▁program . ▁The ▁modifications ▁had ▁various ▁effects . ▁The ▁ability ▁to ▁man ▁and ▁deploy