▁Ple iku , ▁Dar lac ▁and ▁the ▁Kon ▁T um ▁Provin ces , ▁last ing ▁from ▁ 6 ▁April ▁to ▁ 1 1 ▁October ▁ 1 9 6 7 . ▁ ▁Background ▁The ▁operation ▁was ▁a ▁continu ation ▁of ▁the ▁recently ▁concluded ▁Operation ▁Sam ▁Houston ▁in ▁the ▁same ▁general ▁area . ▁ 4 th ▁Infantry ▁Division ▁commander ▁M G ▁William ▁R . ▁Pe ers ▁planned ▁a ▁defense ▁in ▁depth ▁against ▁People ' s ▁Army ▁of ▁Vietnam ▁( PA V N ) ▁inc urs ions ▁from ▁Base ▁Are as ▁ 7 0 1 ▁and ▁ 7 0 2 ▁across ▁the ▁Camb od ian ▁border . ▁ ▁Operation ▁ ▁Operation ▁Francis ▁Mar ion ▁comm enced ▁on ▁ 6 ▁April . ▁The ▁ 1 st ▁Brigade , ▁ 4 th ▁Infantry ▁Division ▁deployed ▁in ▁an ▁arc ▁ 2 0   km ▁east ▁of ▁the ▁Camb od ian ▁border ▁along ▁Highway ▁ 1 4 B ▁and ▁the ▁north - s outh ▁line ▁of ▁U . S . ▁Special ▁Forces ▁cam ps ▁at ▁P lei ▁D jer eng , ▁ Đ ứ c ▁C ơ ▁and ▁P lei ▁Me , ▁with ▁the ▁ 2 nd ▁Brigade ▁held ▁as ▁a ▁reserve ▁force . ▁Special ▁Forces , ▁C ID G ▁units ▁and ▁the ▁ 4 th ▁Division ' s ▁long - range ▁reconna issance ▁teams ▁would ▁search ▁the ▁area ▁west ▁of ▁this ▁line ▁to ▁the ▁Camb od ian ▁border . ▁The ▁Army ▁of ▁the ▁Republic ▁of ▁Vietnam ▁( AR V N ) ▁ 2 3 rd ▁Division ▁extended ▁the ▁screen