Following two decisive victories over the Byzantines at Acheloos (near the present-day city of Pomorie) and Katasyrtai (near Constantinople), Bulgaria declared the autonomous Bulgarian Archbishopric as autocephalous and elevated it to the rank of Patriarchate at an ecclesiastical and national council held in 919. After Bulgaria and the Byzantine Empire signed a peace treaty in 927 that concluded the 20-year-long war between them, the Patriarchate of Constantinople recognised the autocephalous status of the Bulgarian Orthodox Church and acknowledged its patriarchal dignity.