▁mut ual ▁exhaust ion . ▁German ▁arm ies ▁prepared ▁elaborate ▁def ensive ▁positions ▁on ▁the ▁western ▁front ▁with ▁tren ches , ▁bar bed ▁wire ▁and ▁concrete ▁strong - points ▁back ed ▁by ▁art illery , ▁rif les ▁and ▁machine ▁guns ▁which ▁until ▁ 1 9 1 7 , ▁were ▁sufficient ▁to ▁inf lict ▁mass ▁losses ▁on ▁attack ing ▁inf antry ▁and ▁restrict ▁the ▁Franco - B rit ish ▁arm ies ▁to ▁minor ▁g ains ▁in ▁ground . ▁T act ical ▁development ▁on ▁the ▁Western ▁Front ▁in ▁ 1 9 1 7 ▁began ▁to ▁return ▁mob ility ▁to ▁the ▁battle field ▁and ▁a ▁form ▁of ▁semi - open ▁war fare ▁developed . ▁Much ▁inter - war ▁military ▁thinking ▁was ▁influenced ▁by ▁the ▁cost ▁of ▁off ens ives ▁fought ▁for ▁strateg ic ▁reasons , ▁in ▁circumstances ▁of ▁def ensive ▁oper ational ▁and ▁tact ical ▁domin ance . ▁In ▁World ▁War ▁II , ▁the ▁Western ▁Al lies ▁from ▁ 1 9 3 9 – 1 9 4 0 ▁avoided ▁an ▁off ensive , ▁int ending ▁to ▁wait ▁until ▁Franco - B rit ish ▁re arm ament ▁had ▁m ature d ▁and ▁the ▁block ade ▁of ▁Germany ▁had ▁und erm ined ▁its ▁war ▁economy , ▁then ▁in ▁ 1 9 4 1 ▁or ▁ 1 9 4 2 , ▁res ume ▁the ▁fire power ▁war fare ▁of ▁ 1 9 1 8 . ▁ ▁Notes ▁ ▁References ▁▁ ▁John ▁R . ▁Carter , ▁Air power ▁and ▁the ▁Cult ▁of ▁the ▁Off ensive ▁ ▁Dup uy , ▁Tre