s ▁of ▁other ▁princes . ▁Land wehr s ▁were ▁a ▁clear ▁border ▁mark ing ▁and , ▁at ▁the ▁same ▁time , ▁when ▁they ▁defined ▁the ▁external ▁border ▁to ▁another ▁territory , ▁also ▁a ▁custom s ▁border . ▁Even ▁within ▁a ▁territory , ▁there ▁were ▁sometimes ▁land wehr s ▁which ▁separated ▁the ▁individual ▁districts ▁( Ä m ter ) ▁from ▁one ▁another ▁by ▁the ▁inclusion ▁of ▁streams ▁and ▁other ▁natural ▁obst acles . ▁These ▁' internal ' ▁or ▁' inter mediate ' ▁land wehr s ▁( Z w ischen land we hren ), ▁were ▁generally ▁not ▁as ▁elaborate ▁as ▁those ▁on ▁the ▁external ▁borders . ▁ ▁One ▁particular ▁variant ▁was ▁the ▁so - called ▁let zi ▁in ▁Switzerland , ▁where ▁it ▁was ▁often ▁sufficient ▁just ▁to ▁secure ▁the ▁access ▁routes ▁to ▁a ▁valley . ▁Many ▁of ▁the ▁batt les ▁of ▁the ▁Old ▁Confeder ation ▁with ▁the ▁H abs burg s ▁took ▁place ▁at ▁such ▁let z is , ▁such ▁as ▁Battle ▁of ▁M org arten , ▁Battle ▁of ▁Nä f els ▁and ▁Battle ▁of ▁St oss . ▁ ▁Some ▁land wehr s ▁also ▁function ed ▁as ▁a ▁form ▁of ▁out work ▁for ▁for tr esses . ▁They ▁were ▁built ▁with ▁the ▁character ▁of ▁field works ▁as ▁a ▁first ▁line ▁of ▁defence ▁against ▁enemy ▁attack . ▁U sed ▁until ▁the ▁Modern ▁Era , ▁they ▁were ▁designed ▁militar ily , ▁in ▁the ▁form ▁of ▁che v aux ▁de ▁fr ise , ▁to ▁force ▁the ▁ ▁attack er ▁of ▁a ▁for tr ess ▁into ▁having ▁to ▁conduct