▁the ▁Mexican ▁revolution aries ▁under ▁Cort ina , ▁or ▁be ▁executed ▁by ▁him ▁as ▁enemies ▁of ▁his ▁country . ▁ ▁Cort ina ▁and ▁his ▁forces ▁are ▁soon ▁taken ▁by ▁Col . ▁Max imo ▁N ex or , ▁commander ▁of ▁the ▁Republican ▁Army ▁of ▁the ▁Mexican ▁Government , ▁and ▁given ▁the ▁choice ▁of ▁fighting ▁for ▁Santa ▁Anna ▁against ▁the ▁ag gress or ▁U . S . ▁Army , ▁or ▁be ▁executed ▁as ▁tra itors ▁and ▁band its . ▁Cort ina ▁rel uct antly ▁surr enders ▁himself ▁and ▁his ▁revolution aries ▁under ▁N ex or ' s ▁command . ▁R iley ▁is ▁made ▁a ▁captain , ▁in ▁charge ▁of ▁all ▁the ▁Irish - imm igr ant ▁U . S . ▁soldiers ▁who ▁have ▁come ▁over ▁to ▁the ▁Mexican ▁side ▁in ▁increasing ly ▁large ▁numbers , ▁( as ▁General ▁Zach ary ▁Taylor ▁puts ▁it , ▁" because ▁of ▁sex , ▁sain ts ▁and ▁sad ism "). ▁For ▁encourag ement ▁they ▁are ▁given ▁their ▁own ▁green ▁flag ▁as ▁the ▁Saint ▁Patrick ' s ▁Battalion . ▁ ▁Several ▁key ▁battle ▁engag ements ▁are ▁highlight ed , ▁with ▁dates , ▁and ▁a ▁ce ase - fire ▁is ▁reached . ▁Meanwhile , ▁the ▁U . S . ▁Senate ▁is ▁threaten ing ▁to ▁im pe ach ▁President ▁Pol k ▁as ▁world ▁opinion ▁turns ▁against ▁U . S . ▁ag gression ▁and ▁the ▁invasion ▁of ▁the ▁Republic ▁of ▁Mexico . ▁The ▁ce ase - fire ▁is ▁soon ▁viol ated ▁and ▁host ilities ▁res ume . ▁Gen . ▁Zach ary ▁Taylor , ▁unlike