▁his ▁force ▁to ▁the ▁north . ▁Grant ▁captured ▁the ▁city ▁and ▁then ▁faced ▁to ▁the ▁west ▁to ▁approach ▁V icks burg . ▁ ▁John ston ▁began ▁to ▁move ▁his ▁force ▁west ▁to ▁join ▁P ember ton ▁when ▁he ▁heard ▁of ▁that ▁general ' s ▁defeat ▁at ▁Champion ▁Hill ▁( May ▁ 1 6 ) ▁and ▁Big ▁Black ▁River ▁Bridge ▁( May ▁ 1 7 ). ▁The ▁surv iv ors ▁retre ated ▁to ▁the ▁fort ifications ▁of ▁V icks burg . ▁John ston ▁ur ged ▁P ember ton ▁to ▁avoid ▁being ▁surrounded ▁by ▁abandon ing ▁the ▁city ▁and ▁to ▁join ▁forces ▁with ▁John ston ' s ▁troops , ▁out number ing ▁Grant , ▁but ▁Davis ▁had ▁ordered ▁P ember ton ▁to ▁defend ▁the ▁city ▁as ▁his ▁highest ▁priority . ▁Grant ▁launched ▁two ▁un success ful ▁assault s ▁against ▁the ▁fort ifications ▁and ▁then ▁settled ▁in ▁for ▁a ▁sie ge . ▁The ▁soldiers ▁and ▁civ ili ans ▁in ▁the ▁surrounded ▁city ▁waited ▁in ▁vain ▁for ▁John ston ' s ▁small ▁force ▁to ▁come ▁to ▁their ▁rescue . ▁By ▁late ▁May ▁John ston ▁had ▁accum ulated ▁about ▁ 2 4 , 0 0 0 ▁men ▁but ▁wanted ▁additional ▁rein for c ements ▁before ▁moving ▁forward . ▁He ▁considered ▁ordering ▁B rag g ▁to ▁send ▁these ▁rein for c ements , ▁but ▁was ▁concerned ▁that ▁this ▁could ▁result ▁in ▁the ▁loss ▁of ▁Tennessee . ▁He ▁also ▁b icker ed ▁with ▁President ▁Davis ▁about ▁whether ▁the ▁order ▁sending ▁him ▁to ▁Mississippi ▁could ▁be ▁constru ed ▁as ▁removing ▁him