ived ▁in ▁February ▁ 1 9 1 7 . ▁Prior ▁to ▁the ▁Battle ▁of ▁V im y ▁R idge ▁( 9 – 1 2 ▁April ▁ 1 9 1 7 ), ▁the ▁British ▁t unn elling ▁companies ▁secret ly ▁laid ▁a ▁series ▁of ▁explos ive ▁charges ▁under ▁German ▁positions ▁in ▁an ▁effort ▁to ▁destroy ▁surface ▁fort ifications ▁before ▁the ▁assault . ▁The ▁original ▁plan ▁had ▁called ▁for ▁ 1 7 ▁mines ▁and ▁ 9 ▁W omb at ▁charges ▁to ▁support ▁the ▁inf antry ▁attack , ▁of ▁which ▁ 1 3 ▁( poss ibly ▁ 1 4 ) ▁mines ▁and ▁ 8 ▁W omb at ▁charges ▁were ▁eventually ▁laid . ▁At ▁the ▁same ▁time , ▁ 1 9 ▁cr ater ▁groups ▁existed ▁along ▁this ▁section ▁of ▁the ▁Western ▁Front , ▁each ▁with ▁several ▁large ▁cr aters . ▁In ▁order ▁to ▁assess ▁the ▁consequences ▁of ▁inf antry ▁having ▁to ▁advance ▁across ▁cr ater ed ▁ground ▁after ▁a ▁min ing ▁attack , ▁officers ▁from ▁the ▁Canadian ▁Corps ▁visited ▁La ▁Bo iss elle ▁and ▁F ric ourt ▁where ▁the ▁mines ▁on ▁the ▁first ▁day ▁of ▁the ▁Som me ▁had ▁been ▁blow n . ▁Their ▁reports ▁and ▁the ▁experience ▁of ▁the ▁Canad ians ▁at ▁St ▁E lo i ▁in ▁April ▁ 1 9 1 6 ▁– ▁where ▁mines ▁had ▁so ▁alter ed ▁and ▁dam aged ▁the ▁landscape ▁as ▁to ▁render ▁occupation ▁of ▁the ▁mine ▁cr aters ▁by ▁the ▁inf antry ▁all ▁but ▁impossible ▁– , ▁led ▁to ▁the ▁decision ▁to ▁remove ▁off ensive ▁min ing ▁from ▁the ▁central