▁K aw ag uch i ' s ▁troops ▁under ▁Colonel ▁Ak inos u ke ▁O ka ' s ▁local ▁command . ▁In ▁the ▁second ▁action , ▁between ▁ 6 ▁and ▁ 9 ▁October , ▁a ▁larger ▁force ▁of ▁U . S . ▁Mar ines ▁crossed ▁the ▁Mat an ik au ▁River , ▁attacked ▁newly ▁land ed ▁Japanese ▁forces ▁from ▁the ▁ 2 nd ▁( Send ai ) ▁Infantry ▁Division ▁under ▁the ▁command ▁of ▁gener als ▁Mas ao ▁Mar uy ama ▁and ▁Y um io ▁Nas u ▁and ▁inf lic ted ▁heavy ▁cas ual ties ▁on ▁the ▁Japanese ▁ 4 th ▁Infantry ▁Regiment . ▁The ▁second ▁action ▁forced ▁the ▁Japanese ▁to ▁retre at ▁from ▁their ▁positions ▁east ▁of ▁the ▁Mat an ik au . ▁ ▁In ▁the ▁meant ime , ▁Major ▁General ▁Mill ard ▁F . ▁Harm on , ▁commander ▁of ▁U . S . ▁Army ▁forces ▁in ▁the ▁South ▁Pacific , ▁convinced ▁Vice ▁Admir al ▁Robert ▁L . ▁Gh orm ley , ▁commander ▁of ▁Al lied ▁forces ▁in ▁the ▁South ▁Pacific ▁Area , ▁that ▁U . S . ▁Marine ▁forces ▁on ▁Gu adal can al ▁needed ▁to ▁be ▁rein for ced ▁immediately ▁if ▁the ▁Al lies ▁were ▁to ▁successfully ▁defend ▁the ▁island ▁from ▁the ▁next ▁expected ▁Japanese ▁off ensive . ▁Thus ▁on ▁ 1 3 ▁October , ▁a ▁naval ▁con voy ▁delivered ▁the ▁ 2 , 8 3 7 - strong ▁ 1 6 4 th ▁U . S . ▁Infantry ▁Regiment , ▁a ▁North ▁Dak ota ▁Army ▁National ▁Guard ▁formation ▁from ▁the