ing ▁It ali ans ▁to ▁the ▁left ▁of ▁these ▁positions ▁exposed ▁and ▁contributed ▁to ▁their ▁defeat . ▁ ▁In ▁the ▁center ▁the ▁ 4 th ▁Col onial ▁Regiment ▁moved ▁against ▁the ▁hill ▁named ▁by ▁the ▁Bulg ari ans ▁" S ht ab na ▁Vis och ina " ( its ▁French ▁design ation ▁was ▁Pit on ▁Ja une ) and ▁managed ▁to ▁advance ▁without ▁initially ▁being ▁sp otted ▁as ▁many ▁of ▁the ▁Bulgar ian ▁obser ves ▁had ▁been ▁killed ▁or ▁wounded . ▁The ▁few ▁that ▁had ▁surv ived ▁the ▁French ▁bomb ard ment ▁however ▁were ▁able ▁to ▁fire ▁their ▁red ▁fla irs ▁and ▁signal ▁the ▁def enders ▁as ▁the ▁attack ers ▁reached ▁the ▁bar bed ▁wire ▁lines . ▁Al most ▁immediately ▁the ▁Bulgar ian ▁inf antry ▁came ▁out ▁from ▁its ▁sh el ters ▁or ▁hide - outs ▁into ▁the ▁tren ches ▁and ▁opened ▁heavy ▁rif le ▁and ▁machine ▁gun ▁fire ▁on ▁the ▁French . ▁This ▁caught ▁the ▁first ▁wave ▁of ▁attack ers ▁by ▁surprise ▁and ▁forced ▁to ▁retre at ▁which ▁in ▁turn ▁caused ▁the ▁next ▁two ▁waves ▁of ▁French ▁inf antry ▁to ▁wa ver ▁and ▁eventually ▁withdraw . ▁While ▁they ▁were ▁retre ating ▁the ▁French ▁came ▁under ▁Bulgar ian ▁art illery ▁fire ▁and ▁suffered ▁heavy ▁cas ual ties . ▁ ▁To ▁the ▁right ▁the ▁French ▁ 3 7 th ▁Col onial ▁Regiment ▁had ▁better ▁luck ▁and ▁managed ▁to ▁enter ▁and ▁occup y ▁the ▁tren ches ▁on ▁Hill ▁" V ask ova ▁Vis och ina " ( T ran che es ▁r oug es )