▁install ations ▁in ▁the ▁Liv no ▁Valley , ▁and ▁prevent ▁any ▁Part isan ▁withdraw al ▁to ▁the ▁south ▁of ▁Dr var ▁by ▁attack ing ▁through ▁Bos ans ki ▁Gra h ovo ▁toward ▁Dr var . ▁ ▁The ▁ 3 6 9 th ▁Re con na issance ▁Battalion ▁of ▁the ▁ 3 6 9 th ▁( C ro at ian ) ▁Infantry ▁Division ▁( C ro at ian ▁leg ion na ires ), ▁under ▁the ▁command ▁of ▁the ▁ 1 0 5 th ▁SS ▁Re con na issance ▁Battalion , ▁were ▁to ▁advance ▁from ▁Liv no ▁up ▁the ▁G lam o č ▁Valley ▁against ▁Part isan ▁forces ▁withdraw ing ▁from ▁Dr var ▁to ▁the ▁sout heast . ▁ ▁The ▁ 1 st ▁Regiment ▁of ▁the ▁Brandenburg ▁Division , ▁along ▁with ▁the ▁collaboration ist ▁Ch et nik ▁Din ara ▁Division ▁of ▁M om č ilo ▁ Đ u ji ć , ▁were ▁to ▁advance ▁from ▁Kn in ▁toward ▁Bos ans ki ▁Gra h ovo ▁and ▁conduct ▁special ▁operations ▁against ▁Part is ans ▁in ▁the ▁Pre k aja - Dr var ▁area . ▁ ▁Operation ▁ ▁The ▁off ensive ▁began ▁at ▁ 0 5 : 0 0 ▁on ▁ 2 5 ▁May ▁ 1 9 4 4 ▁with ▁the ▁advance ▁of ▁ground ▁forces ▁from ▁their ▁assembly ▁areas ▁surrounding ▁their ▁assigned ▁oper ational ▁areas . ▁About ▁ 0 6 : 3 5 , ▁five ▁squad rons ▁of ▁Luft wa ffe ▁bom bers , ▁including ▁J unk ers ▁Ju ▁ 8 7 ▁ ▁d ive ▁bom bers ,