▁in ▁April ▁ 1 8 3 8 ▁and ▁was ▁appointed ▁a ▁first ▁lieutenant ▁of ▁top ographic ▁engine ers ▁on ▁July ▁ 7 ; ▁on ▁that ▁same ▁day , ▁he ▁received ▁a ▁bre vet ▁promotion ▁to ▁captain ▁for ▁the ▁actions ▁at ▁Jup iter ▁In let ▁and ▁his ▁expl or ations ▁of ▁the ▁Florida ▁Ever gl ades . ▁ ▁On ▁July ▁ 1 0 , ▁ 1 8 4 5 , ▁in ▁Baltimore , ▁John ston ▁married ▁L yd ia ▁M ull igan ▁Sim s ▁Mc L ane ▁( 1 8 2 2 – 1 8 8 7 ), ▁the ▁daughter ▁of ▁Louis ▁Mc L ane ▁and ▁his ▁wife . ▁Her ▁father ▁was ▁the ▁president ▁of ▁the ▁Baltimore ▁and ▁Ohio ▁Rail road , ▁a ▁prominent ▁politician ▁( con gress man ▁and ▁sen ator ▁from ▁Del aware , ▁minister ▁to ▁London , ▁and ▁a ▁member ▁of ▁President ▁Andrew ▁Jackson ' s ▁cabinet ). ▁They ▁had ▁no ▁children . ▁ ▁John ston ▁was ▁enthus i astic ▁about ▁the ▁out break ▁of ▁the ▁Mexican – American ▁War . ▁He ▁served ▁on ▁the ▁staff ▁of ▁L t . ▁Gen . ▁Win field ▁Scott ▁in ▁the ▁Sie ge ▁of ▁Ver ac ru z , ▁having ▁been ▁chosen ▁by ▁Scott ▁to ▁be ▁the ▁officer ▁carrying ▁the ▁demand ▁for ▁surrender ▁before hand ▁to ▁the ▁provincial ▁governor . ▁He ▁was ▁in ▁the ▁v angu ard ▁of ▁the ▁movement ▁in land ▁under ▁Brig . ▁Gen . ▁David ▁E . ▁Tw ig gs ▁and ▁was ▁sever ely ▁wounded ▁by ▁g rap es hot ▁performing ▁reconna