▁ended . ▁Next ▁day ▁General ▁Paul ▁von ▁H inden burg ▁was ▁appointed ▁ ▁( O ber ▁Ost , ▁Commander - in - Ch ief ▁of ▁German ▁Arm ies ▁in ▁the ▁Eastern ▁Theatre ). ▁On ▁ 2 1 ▁September , ▁Jar os law ▁in ▁Gal icia ▁was ▁taken ▁by ▁the ▁Russian ▁army . ▁On ▁ 2 4 ▁September , ▁Prz emy ś l ▁was ▁isolated ▁by ▁Russian ▁forces , ▁beginning ▁the ▁First ▁Sie ge ▁as ▁Russian ▁forces ▁conducted ▁the ▁First ▁In vas ion ▁of ▁North ▁Hung ary ▁ ▁Military ▁operations ▁began ▁on ▁the ▁Niem en ▁ ▁but ▁German ▁attacks ▁were ▁susp ended ▁on ▁ 2 9 ▁September . ▁The ▁retre at ▁of ▁Aust ro - H ung arian ▁forces ▁in ▁Gal icia ▁ended ▁and ▁Mar amar os - S zig et ▁was ▁captured ▁by ▁the ▁Russian ▁army ; ▁an ▁Aust ro - H ung arian ▁counter - off ensive ▁began ▁on ▁ 4 ▁October ▁and ▁Mar amar os - S zig et ▁was ▁ret aken . ▁On ▁ 9 ▁October , ▁the ▁First ▁German ▁Off ensive ▁against ▁Wars aw ▁began ▁with ▁the ▁batt les ▁of ▁Wars aw ▁ ▁and ▁I v ang or od ▁ ▁As ▁the ▁situation ▁on ▁the ▁eastern ▁front ▁d eter ior ated ▁in ▁September , ▁the ▁new ▁German ▁high ▁command ▁under ▁General ▁Fal ken h ay n ▁attempted ▁to ▁retrieve ▁the ▁situation ▁in ▁France ▁and ▁inf lict ▁a ▁decis ive ▁defeat . ▁ ▁T act ical ▁develop ments ▁ ▁Oper ations ▁in ▁Belg ium , ▁August – Oct ober ▁