▁surface ▁when ▁South ▁Vietnam ▁inv aded ▁South west ▁C ay , ▁then ▁occupied ▁by ▁the ▁military ▁forces ▁of ▁its ▁w art ime ▁al ly , ▁the ▁Philippines . ▁In ▁order ▁to ▁l ure ▁the ▁Philippines ▁soldiers ▁off ▁South west ▁C ay , ▁it ▁was ▁reported ▁that ▁South ▁Vietnam ese ▁authorities ▁sent ▁prost it utes ▁to ▁the ▁birth day ▁party ▁of ▁the ▁Philipp ine ▁military ▁commander ▁on ▁another ▁island . ▁ ▁While ▁the ▁Philipp ine ▁soldiers ▁left ▁their ▁post ▁to ▁attend ▁the ▁birth day ▁party ▁of ▁their ▁command ing ▁officer , ▁South ▁Vietnam ese ▁soldiers ▁moved ▁in ▁to ▁occup y ▁South west ▁C ay . ▁After ▁the ▁Philippines ▁military ▁realized ▁they ▁had ▁lost ▁their ▁territory , ▁they ▁planned ▁to ▁re take ▁the ▁island ▁from ▁the ▁South ▁Vietnam ese ▁through ▁military ▁force . ▁By ▁the ▁time ▁the ▁Philippines ▁military ▁were ▁able ▁to ▁put ▁their ▁plan ▁into ▁action , ▁the ▁South ▁Vietnam ese ▁had ▁already ▁built ▁a ▁strong ▁defense ▁on ▁South west ▁C ay , ▁thus ▁d eter ring ▁any ▁potential ▁counter - att ack . ▁Later ▁South west ▁C ay ▁would ▁be ▁the ▁first ▁major ▁target ▁for ▁the ▁North ▁Vietnam ese ▁Navy . ▁ ▁P rel ude ▁ ▁North ▁Vietnam ▁On ▁April ▁ 4 , ▁ 1 9 7 5 , ▁the ▁High ▁Command ▁of ▁the ▁V PN ▁and ▁the ▁Command ▁of ▁Military ▁Region ▁ 5 , ▁under ▁the ▁command ▁of ▁General ▁Ch u ▁H uy ▁Man , ▁agreed ▁on ▁a ▁plan ▁to ▁se ize ▁some ▁Spr at ly s ▁and ▁other ▁groups ▁of ▁islands