The siege of Adrianople ( ) in 813 was a part of the wars of the Byzantine Empire with the Bulgarian khan Krum ( Byzantine-Bulgarian Wars ) .

After an unsuccessful Byzantine attempt to murder Killing him ruined Destroying all prospects for negotiations with them , Krum ravaged Destroying much of Eastern Thrace and then turned Change against Adrianople which was still under siege Besieging .

On Krum 's order the population of Adrianople and the surrounding area ( numbering about 10,000 ) was transferred Sending to Bulgarian territory north of the Danube .

Under the peace treaty , concluded Process_end in 815 , Adrianople remained in the Byzantine empire .

The Ottoman Empire also attacked Attack Bulgaria and advanced Cause_to_make_progress in Thrace regaining Recovering Adrianople .