1 4 ▁September , ▁concluded ▁that ▁a ▁decis ive ▁victory ▁could ▁not ▁be ▁achieved ▁on ▁the ▁Western ▁Front ▁and ▁that ▁it ▁was ▁equally ▁unlikely ▁in ▁the ▁east . ▁Fal ken h ay n ▁abandoned ▁ ▁( str ategy ▁of ▁anni h ilation ) ▁and ▁attempted ▁to ▁create ▁the ▁conditions ▁for ▁peace ▁with ▁one ▁of ▁Germany ' s ▁enemies , ▁by ▁ ▁( str ategy ▁of ▁exhaust ion ), ▁to ▁enable ▁Germany ▁to ▁concent rate ▁its ▁resources ▁decis ively ▁to ▁defeat ▁the ▁remaining ▁oppon ents . ▁ ▁Over ▁the ▁winter ▁l ull , ▁the ▁French ▁army ▁established ▁the ▁theoretical ▁basis ▁of ▁off ensive ▁tren ch ▁war fare , ▁origin ating ▁many ▁of ▁the ▁methods ▁which ▁became ▁standard ▁for ▁the ▁rest ▁of ▁the ▁war . ▁In fil tr ation ▁tact ics , ▁in ▁which ▁dispers ed ▁form ations ▁of ▁inf antry ▁were ▁followed ▁by ▁ ▁( tr en ch ▁clean ers ), ▁to ▁capture ▁by - pass ed ▁strong ▁points ▁were ▁prom ul g ated . ▁Art illery ▁observation ▁from ▁aircraft ▁and ▁cre eping ▁bar rages , ▁were ▁first ▁used ▁system atically ▁in ▁the ▁Second ▁Battle ▁of ▁Ar to is ▁from ▁ 9 ▁May ▁to ▁ 1 8 ▁June ▁ 1 9 1 5 . ▁Fal ken h ay n ▁issued ▁memor anda ▁on ▁▁ 1 9 1 5 , ▁to ▁govern ▁def ensive ▁battle ▁on ▁the ▁Western ▁Front , ▁in ▁which ▁the ▁existing ▁front ▁line ▁was ▁to ▁be ▁fort ified ▁and ▁to ▁be ▁held ▁in def initely ▁with ▁small ▁numbers ▁of ▁troops , ▁to