▁ 3 rd ▁Reserve ▁Division ▁had ▁engaged ▁the ▁Rus si ans ' ▁XX II ▁Corps ▁even ▁further ▁south , ▁and ▁after ▁a ▁fier ce ▁battle ▁forced ▁them ▁to ▁fall ▁back ▁sout heast ward ; ▁its ▁commander ▁w ired ▁R enn enk ampf ▁he ▁had ▁been ▁attacked ▁and ▁defeated ▁near ▁Ly ck , ▁and ▁could ▁do ▁nothing ▁but ▁withdraw . ▁R enn enk ampf ▁ordered ▁a ▁counter off ensive ▁in ▁the ▁north ▁to ▁buy ▁time ▁to ▁reform ▁his ▁lines , ▁man aging ▁to ▁push ▁the ▁German ▁XX ▁Corps ▁back ▁a ▁number ▁of ▁miles . ▁However , ▁the ▁Germ ans ▁did ▁not ▁stop ▁to ▁reform ▁their ▁lines ▁but ▁instead ▁continued ▁their ▁adv ances ▁in ▁the ▁south ▁and ▁north . ▁This ▁left ▁the ▁vict orious ▁Russian ▁troops ▁isolated ▁but ▁still ▁able ▁to ▁retre at ▁to ▁new ▁lines ▁being ▁set ▁up ▁in ▁the ▁east . ▁ ▁Now ▁the ▁battle ▁turned ▁decis ively ▁in ▁the ▁Germ ans ' ▁favor . ▁By ▁ 1 1 ▁September ▁the ▁Rus si ans ▁had ▁been ▁pushed ▁back ▁to ▁a ▁line ▁running ▁from ▁In ster burg ▁to ▁An ger burg ▁in ▁the ▁north , ▁with ▁a ▁huge ▁fl ank ing ▁man eu ver ▁developing ▁to ▁the ▁south . ▁It ▁was ▁at ▁this ▁point ▁that ▁the ▁threat ▁of ▁enc irc lement ▁appeared ▁possible . ▁R enn enk ampf ▁ordered ▁a ▁general ▁retre at ▁toward ▁the ▁Russian ▁border , ▁which ▁happened ▁rapidly ▁under ▁the ▁protection ▁of ▁a ▁strong ▁rear ▁guard . ▁It ▁was ▁this ▁speed ▁that ▁enabled ▁the ▁retre ating ▁Russian ▁troops ▁to ▁escape ▁the