under ▁the ▁fert ile ▁plain ▁of ▁Pel ag onia , ▁where ▁they ▁captured ▁many ▁prisoners ▁and ▁liv est ock . ▁So on ▁after , ▁Bas il ▁II ▁placed ▁Di ogen es ▁in ▁charge ▁of ▁the ▁tag m ata ▁of ▁the ▁Sch ol ai ▁of ▁the ▁West ▁and ▁of ▁Th ess al onica , ▁and ▁task ed ▁him ▁with ▁purs uing ▁Ts ar ▁Ivan ▁Vlad is lav . ▁The ▁Bulgar ian ▁r uler ▁set ▁up ▁an ▁amb ush ▁for ▁his ▁purs u ers , ▁but ▁Bas il ▁was ▁informed ▁in ▁time , ▁and ▁led ▁the ▁rest ▁of ▁his ▁troops ▁to ▁Di ogen es ' ▁aid , ▁scatter ing ▁the ▁Bulg ari ans . ▁ ▁After ▁Ivan ▁Vlad is lav ' s ▁death ▁in ▁February ▁ 1 0 1 8 , ▁Di ogen es ▁was ▁charged ▁with ▁mo pping ▁up ▁the ▁last ▁remaining ▁cent res ▁of ▁Bulgar ian ▁resistance . ▁He ▁took ▁S irm ium ▁and ▁was ▁named ▁its ▁commander ▁( arch on ); ▁his ▁authority ▁extended ▁over ▁the ▁v ass al ▁Ser bian ▁state lets ▁of ▁Ra š ka . ▁His ▁title ▁was ▁possibly ▁that ▁of ▁" str ateg os ▁of ▁Ser bia " ▁( G reek : ▁ σ τ ρ α τ η γ ό ς ▁ Σ ε ρ β ί α ς ), ▁which ▁is ▁att ested ▁in ▁a ▁se al ▁attributed ▁to ▁him . ▁Di ogen es ▁was ▁ordered ▁by ▁Bas il ▁II ▁to ▁sub due ▁S erm on , ▁the ▁r uler ▁of ▁S irm ium , ▁to