▁gap ▁between ▁the ▁ 1 st ▁and ▁ 2 nd ▁arm ies . ▁The ▁BE F ▁advanced ▁from ▁ ▁crossed ▁the ▁Pet it ▁Mor in , ▁captured ▁brid ges ▁over ▁the ▁Mar ne ▁and ▁established ▁a ▁bridge head ▁ ▁deep . ▁The ▁Fif th ▁Army ▁also ▁advanced ▁into ▁the ▁gap ▁and ▁by ▁ 8 ▁September , ▁had ▁crossed ▁the ▁Pet it ▁Mor in , ▁which ▁forced ▁Bü low ▁to ▁withdraw ▁the ▁right ▁fl ank ▁of ▁the ▁ 2 nd ▁Army . ▁Next ▁day ▁the ▁Fif th ▁Army ▁rec ross ed ▁the ▁Mar ne ▁and ▁the ▁German ▁ 1 st ▁and ▁ 2 nd ▁arm ies ▁began ▁to ▁ret ire ▁as ▁the ▁French ▁N inth , ▁Four th ▁and ▁Third ▁Arm ies ▁fought ▁def ensive ▁batt les ▁against ▁the ▁ 3 rd ▁Army ▁which ▁then ▁had ▁to ▁retre at ▁with ▁the ▁ 1 st ▁and ▁ 2 nd ▁arm ies ▁on ▁ 9 ▁September . ▁ ▁Further ▁east , ▁the ▁Third ▁Army ▁was ▁forced ▁back ▁to ▁the ▁west ▁of ▁Verd un ▁as ▁German ▁attacks ▁were ▁made ▁on ▁the ▁Me use ▁He ights ▁to ▁the ▁south - east ▁but ▁managed ▁to ▁maintain ▁contact ▁with ▁Verd un ▁and ▁the ▁Four th ▁Army ▁to ▁the ▁west . ▁German ▁attacks ▁against ▁the ▁Second ▁Army ▁south ▁of ▁Verd un ▁from ▁ 5 ▁September , ▁almost ▁forced ▁the ▁French ▁to ▁retre at ▁but ▁on ▁ 8 ▁September , ▁the ▁crisis ▁e ased . ▁By ▁ 1 0 ▁September , ▁the ▁German ▁arm ies ▁west ▁of ▁Verd un ▁were ▁retre ating