▁points ▁for ▁a ▁campaign ▁with ▁the ▁event ual ▁goal ▁of ▁isol ating ▁the ▁major ▁Japanese ▁base ▁at ▁R aba ul ▁while ▁also ▁supporting ▁the ▁Al lied ▁New ▁Guinea ▁campaign . ▁The ▁land ings ▁initi ated ▁the ▁six - month - long ▁Gu adal can al ▁campaign . ▁ ▁T aking ▁the ▁Japanese ▁by ▁surprise , ▁by ▁night fall ▁on ▁ 8 ▁August , ▁the ▁ 1 1 , 0 0 0 ▁Al lied ▁troops — under ▁the ▁command ▁of ▁then ▁Major ▁General ▁Alexander ▁V ande gr ift ▁and ▁mainly ▁consisting ▁of ▁U . S . ▁Marine ▁Corps ▁units — had ▁secured ▁Tul agi ▁and ▁nearby ▁small ▁islands , ▁as ▁well ▁as ▁an ▁air field ▁under ▁construction ▁at ▁L ung a ▁Point ▁on ▁Gu adal can al . ▁The ▁air field ▁was ▁later ▁named ▁" H end erson ▁Field " ▁by ▁Al lied ▁forces . ▁The ▁Al lied ▁aircraft ▁that ▁subsequently ▁operated ▁out ▁of ▁the ▁air field ▁became ▁known ▁as ▁the ▁" C act us ▁Air ▁Force " ▁( C AF ) ▁after ▁the ▁Al lied ▁cod ename ▁for ▁Gu adal can al . ▁To ▁protect ▁the ▁air field , ▁the ▁U . S . ▁Mar ines ▁established ▁a ▁per imeter ▁defense ▁around ▁L ung a ▁Point . ▁ ▁In ▁response ▁to ▁the ▁Al lied ▁land ings ▁on ▁Gu adal can al , ▁the ▁Japanese ▁Imperial ▁General ▁Head quarters ▁assigned ▁the ▁Imperial ▁Japanese ▁Army ' s ▁ 1 7 th ▁Army — a ▁corps - s ized ▁command ▁based ▁at ▁R aba ul ▁and