▁Middle ▁Tennessee ▁and ▁withdraw ▁to ▁the ▁city ▁of ▁Ch att ano oga , ▁suffering ▁only ▁ 5 6 9 ▁Union ▁cas ual ties ▁along ▁the ▁way . ▁General - in - ch ief ▁Maj . ▁Gen . ▁Henry ▁W . ▁Halle ck ▁and ▁President ▁Abraham ▁Lincoln ▁were ▁ins istent ▁that ▁Rose cr ans ▁move ▁quickly ▁to ▁take ▁Ch att ano oga . ▁Se izing ▁the ▁city ▁would ▁open ▁the ▁door ▁for ▁the ▁Union ▁to ▁advance ▁toward ▁Atlanta ▁and ▁the ▁heart land ▁of ▁the ▁South . ▁Ch att ano oga ▁was ▁a ▁vital ▁rail ▁hub ▁( with ▁lines ▁going ▁north ▁toward ▁Nash ville ▁and ▁Kno x ville ▁and ▁south ▁toward ▁Atlanta ), ▁and ▁an ▁important ▁manufact uring ▁center ▁for ▁the ▁production ▁of ▁iron ▁and ▁co ke , ▁located ▁on ▁the ▁navig able ▁Tennessee ▁River . ▁Situ ated ▁between ▁Look out ▁Mountain , ▁Mission ary ▁R idge , ▁R acco on ▁Mountain , ▁and ▁String er ' s ▁R idge , ▁Ch att ano oga ▁occupied ▁an ▁important , ▁def ens ible ▁position . ▁ ▁Although ▁Bra xt on ▁B rag g ' s ▁Army ▁of ▁Tennessee ▁had ▁about ▁ 5 2 , 0 0 0 ▁men ▁at ▁the ▁end ▁of ▁July , ▁the ▁Confeder ate ▁government ▁merged ▁the ▁Department ▁of ▁East ▁Tennessee , ▁under ▁Maj . ▁Gen . ▁Simon ▁B . ▁Buck ner , ▁into ▁B rag g ' s ▁Department ▁of ▁Tennessee , ▁which ▁added ▁ 1 7 , 8 0 0 ▁men ▁to ▁B rag g ' s ▁army , ▁a ▁total