▁Second ▁Army ▁inv aded ▁from ▁the ▁south , ▁hoping ▁to ▁cut ▁the ▁Germ ans ▁off ▁in ▁the ▁area ▁around ▁the ▁city . ▁ ▁However , ▁during ▁their ▁advance ▁Y akov ▁Zh il in sky , ▁Chief ▁of ▁Staff ▁of ▁the ▁Imperial ▁Russian ▁Army , ▁made ▁a ▁strateg ic ▁mistake ▁by ▁separ ating ▁two ▁large ▁Russian ▁arm ies ▁and ▁ur ging ▁them ▁to ▁move ▁rapidly ▁over ▁a ▁margin ally ▁traffic able ▁terrain ▁in ▁response ▁to ▁the ▁requests ▁of ▁the ▁French ▁for ▁an ▁early ▁off ensive . ▁As ▁a ▁result , ▁the ▁arm ies ▁approached ▁in ▁a ▁poor ly ▁coordin ated ▁manner , ▁being ▁isolated ▁from ▁each ▁other ▁by ▁terrain ▁obst acles , ▁and ▁before ▁the ▁log ist ical ▁base ▁could ▁be ▁established , ▁the ▁troops ▁were ▁worn ▁down ▁by ▁a ▁rapid ▁march ▁and ▁had ▁to ▁face ▁fresh ▁German ▁troops . ▁ ▁The ▁Germ ans ▁developed ▁a ▁plan ▁to ▁rapidly ▁move ▁their ▁forces ▁to ▁surr ound ▁the ▁Second ▁Army ▁as ▁it ▁moved ▁north ward ▁over ▁some ▁particularly ▁h illy ▁terrain . ▁The ▁danger ▁was ▁that ▁the ▁First ▁Army ▁would ▁turn ▁to ▁their ▁aid , ▁thereby ▁fl ank ing ▁the ▁German ▁forces . ▁However , ▁the ▁Rus si ans ▁broadcast ▁their ▁daily ▁march ing ▁orders ▁" in ▁the ▁clear " ▁on ▁the ▁radio , ▁and ▁the ▁Germ ans ▁learned ▁that ▁the ▁First ▁Army ▁was ▁continu ing ▁to ▁move ▁away ▁from ▁the ▁Second . ▁Using ▁rail ways ▁in ▁the ▁area , ▁the ▁German ▁forces ▁man eu ver ed ▁and ▁eventually ▁surrounded ▁and ▁destroyed ▁the ▁Second ▁Army ▁at