▁its ▁doctrine ▁on ▁air ▁strik es ▁that ▁combined ▁the ▁air ▁groups ▁within ▁car rier ▁divisions , ▁rather ▁than ▁each ▁individual ▁car rier . ▁When ▁more ▁than ▁one ▁car rier ▁division ▁was ▁operating ▁together , ▁the ▁divisions ' ▁air ▁groups ▁were ▁combined ▁with ▁each ▁other . ▁ ▁This ▁doctrine ▁of ▁combined , ▁mass ed , ▁car rier ▁air ▁attack ▁groups ▁was ▁the ▁most ▁advanced ▁of ▁its ▁kind ▁of ▁all ▁the ▁world ' s ▁nav ies . ▁ ▁The ▁I J N , ▁however , ▁remained ▁concerned ▁that ▁concentr ating ▁all ▁of ▁its ▁carri ers ▁together ▁would ▁render ▁them ▁vulner able ▁to ▁being ▁w ip ed ▁out ▁all ▁at ▁once ▁by ▁a ▁massive ▁enemy ▁air ▁or ▁surface ▁strike . ▁Thus , ▁the ▁I J N ▁developed ▁a ▁comprom ise ▁solution ▁in ▁which ▁the ▁fleet ▁carri ers ▁would ▁operate ▁closely ▁together ▁within ▁their ▁car rier ▁divisions ▁but ▁the ▁divisions ▁themselves ▁would ▁operate ▁in ▁loose ▁rect angular ▁form ations , ▁with ▁approximately ▁ ▁separ ating ▁the ▁carri ers ▁from ▁each ▁other . ▁ ▁Although ▁the ▁concentration ▁of ▁so ▁many ▁fleet ▁carri ers ▁into ▁a ▁single ▁unit ▁was ▁a ▁new ▁and ▁revolution ary ▁off ensive ▁strateg ic ▁concept , ▁the ▁First ▁Air ▁Fle et ▁suffered ▁from ▁several ▁def ensive ▁def ic ien cies ▁which ▁gave ▁it , ▁in ▁Mark ▁Pe att ie ' s ▁words , ▁a ▁glass ▁j aw ': ▁ ▁it ▁could ▁throw ▁a ▁p unch ▁but ▁couldn ' t ▁take ▁one ." ▁Japanese ▁car rier ▁anti - air craft ▁guns ▁and ▁associated ▁fire ▁control ▁systems