▁D , ▁E , ▁and ▁F ▁served ▁for ▁varying ▁periods ▁in ▁Vietnam , ▁from ▁ 1 9 6 6 ▁to ▁ 1 9 7 2 , ▁under ▁the ▁ 9 3 d ▁MP ▁Battalion , ▁the ▁ 4 th ▁Infantry ▁Division , ▁and ▁the ▁ 1 0 1 st ▁Air bor ne ▁Division ▁( A irm obile ), ▁respectively . ▁Company ▁D ▁provided ▁security ▁for ▁the ▁deep ▁water ▁port ▁of ▁Qu i ▁N hon ▁and ▁L R P ▁to ▁protect ▁the ▁fuel ▁pipeline ▁from ▁Qu i ▁N hon ▁to ▁Pl ie ku , ▁Comp an ies ▁E ▁and ▁F ▁performed ▁long ▁range ▁reconna issance ▁miss ions ▁and ▁were ▁later ▁red es ign ated ▁as ▁r anger ▁companies ▁of ▁the ▁ 7 5 th ▁Infantry . ▁▁ ▁The ▁ 1 st ▁Battalion ▁appears ▁to ▁have ▁been ▁re flag ged ▁as ▁the ▁ 4 th ▁Battalion , ▁ 7 th ▁Infantry ▁Regiment ▁in ▁the ▁mid - 1 9 8 0 s . ▁▁ ▁The ▁line age ▁of ▁the ▁former ▁Company ▁B , ▁ 5 8 th ▁Infantry ▁Regiment ▁was ▁re organ ized ▁and ▁red es ign ated ▁effective ▁ 1 ▁July ▁ 1 9 5 7 ▁as ▁Head quarters ▁and ▁Head quarters ▁Company , ▁ 2 d ▁Arm ored ▁R if le ▁Battalion , ▁ 5 8 th ▁Infantry , ▁and ▁assigned ▁to ▁the ▁ 2 d ▁Arm ored ▁Division ▁( organ ic ▁elements ▁concurrent ly ▁constit uted ▁and ▁activ ated ). ▁It ▁was ▁in activ ated ▁ 1 ▁July ▁ 1 9 6 3