▁their ▁control ▁of ▁Armen ia ▁and ▁C il icia , ▁and ▁began ▁prepar ing ▁a ▁renew ed ▁off ensive ▁against ▁Constantin ople . ▁In ▁By z ant ium , ▁the ▁general ▁Leo ▁the ▁Is aur ian ▁( r . ▁ 7 1 7 – 7 4 1 ) ▁had ▁just ▁seized ▁the ▁throne ▁in ▁March ▁ 7 1 7 , ▁when ▁the ▁massive ▁Muslim ▁army ▁under ▁the ▁f amed ▁Um ay y ad ▁prince ▁and ▁general ▁Mas l ama ▁ibn ▁Abd ▁al - Mal ik ▁began ▁moving ▁towards ▁the ▁imperial ▁capital . ▁The ▁C ali ph ate ' s ▁army ▁and ▁n avy , ▁led ▁by ▁Mas l ama , ▁number ed ▁some ▁ 1 2 0 , 0 0 0 ▁men ▁and ▁ 1 , 8 0 0 ▁ships ▁according ▁to ▁the ▁sources . ▁Wh atever ▁the ▁real ▁number , ▁it ▁was ▁a ▁huge ▁force , ▁far ▁larger ▁than ▁the ▁imperial ▁army . ▁Thank fully ▁for ▁Leo ▁and ▁the ▁Empire , ▁the ▁capital ' s ▁sea ▁walls ▁had ▁recently ▁been ▁rep a ired ▁and ▁strength ened . ▁In ▁addition , ▁the ▁em peror ▁concluded ▁an ▁al liance ▁with ▁the ▁Bulgar ▁k han ▁Ter vel , ▁who ▁agreed ▁to ▁har ass ▁the ▁inv aders ' ▁rear . ▁ ▁From ▁July ▁ 7 1 7 ▁to ▁August ▁ 7 1 8 , ▁the ▁city ▁was ▁bes ie ged ▁by ▁land ▁and ▁sea ▁by ▁the ▁Muslim s , ▁who ▁built ▁an ▁extensive ▁double ▁line ▁of ▁circum v all ation ▁and ▁cont rav all ation ▁on