▁def ending ▁Confeder ate ▁control ▁of ▁V icks burg , ▁Mississippi , ▁which ▁was ▁threatened ▁by ▁Union ▁Maj . ▁Gen . ▁U ly ss es ▁S . ▁Grant , ▁first ▁in ▁a ▁series ▁of ▁un success ful ▁man eu vers ▁during ▁the ▁winter ▁of ▁ 1 8 6 2 – 6 3 ▁to ▁the ▁north ▁of ▁the ▁for tr ess ▁city , ▁but ▁followed ▁in ▁April ▁ 1 8 6 3 ▁with ▁an ▁am bit ious ▁campaign ▁that ▁began ▁with ▁Grant ' s ▁Union ▁army ▁crossing ▁the ▁Mississippi ▁River ▁south west ▁of ▁V icks burg . ▁C atch ing ▁L t . ▁Gen . ▁P ember ton ▁by ▁surprise , ▁the ▁Union ▁army ▁w aged ▁a ▁series ▁of ▁successful ▁batt les ▁as ▁it ▁moved ▁n ortheast ▁toward ▁the ▁state ▁capital ▁of ▁Jackson . ▁On ▁May ▁ 9 , ▁the ▁Confeder ate ▁Secretary ▁of ▁War ▁directed ▁John ston ▁to ▁" pro ceed ▁at ▁once ▁to ▁Mississippi ▁and ▁take ▁chief ▁command ▁of ▁the ▁forces ▁in ▁the ▁field ." ▁John ston ▁informed ▁Richmond ▁that ▁he ▁was ▁still ▁med ically ▁un fit , ▁but ▁would ▁obey ▁the ▁order . ▁When ▁he ▁arrived ▁in ▁Jackson ▁on ▁May ▁ 1 3 ▁from ▁Middle ▁Tennessee , ▁he ▁learned ▁that ▁two ▁Union ▁army ▁corps ▁were ▁adv ancing ▁on ▁the ▁city ▁and ▁that ▁there ▁were ▁only ▁about ▁ 6 , 0 0 0 ▁troops ▁available ▁to ▁defend ▁it . ▁John ston ▁ordered ▁a ▁fighting ▁ev acu ation ▁( the ▁Battle ▁of ▁Jackson , ▁May ▁ 1 4 ) ▁and ▁retre ated ▁with