. ▁In ▁December ▁ 1 9 3 9 ▁and ▁January ▁ 1 9 4 0 ▁it ▁was ▁joined ▁by ▁ ▁N os ▁ 1 0 ▁and ▁ 1 1 ▁Line ▁Se ctions ▁provided ▁by ▁the ▁ 2 nd ▁Line ▁unit . ▁ ▁Battle ▁of ▁France ▁▁ ▁Once ▁concentr ated , ▁II ▁Corps ▁moved ▁on ▁ 1 2 ▁October ▁up ▁to ▁the ▁French ▁front ier . ▁When ▁the ▁German ▁off ensive ▁in ▁the ▁west ▁opened ▁on ▁ 1 0 ▁May ▁ 1 9 4 0 . ▁the ▁BE F ▁advanced ▁into ▁Belg ium ▁in ▁accord ance ▁with ▁' Plan ▁D '. ▁However , ▁the ▁German ▁Army ▁broke ▁through ▁the ▁Ar den nes ▁to ▁the ▁east , ▁forcing ▁the ▁BE F ▁to ▁withdraw ▁again , ▁by ▁ 1 9 ▁May ▁the ▁whole ▁force ▁was ▁back ▁across ▁the ▁Es ca ut ▁and ▁then ▁went ▁back ▁to ▁the ▁so - called ▁' Can al ▁Line '. ▁ ▁By ▁ 2 6 ▁May ▁the ▁BE F ▁was ▁cut ▁off ▁and ▁the ▁decision ▁was ▁made ▁to ▁ev acu ate ▁it ▁through ▁D unk irk ▁( Operation ▁Dynam o ), ▁with ▁II ▁Corps ▁acting ▁as ▁fl ank ▁guard ▁against ▁the ▁German ▁pen etr ation ▁where ▁the ▁Belg ian ▁Army ▁had ▁surrender ed . ▁ ▁The ▁last ▁of ▁the ▁BE F ▁who ▁could ▁enter ▁the ▁D unk irk ▁bridge head ▁had ▁done ▁so ▁by ▁ 2 9 ▁May ▁and ▁the ▁ev acu ation ▁progress ed : ▁III ▁Corps ▁went ▁first , ▁followed ▁by ▁II ▁Corps ▁after ▁hand ing ▁over ▁responsibility ▁for