Events By place Europe Egbert of Wessex conquers Mercia and is recognized as Bretwalda. The Saracens ravage the coast of Dalmatia. Oldest known mention of the city of Wiesbaden (approximate date). synod of Mainz Byzantine Empire Theophilus succeeds Michael II as emperor of Byzantium. Egypt The Nile freezes over. Asia The Bai kingdom of Nanzhao captures the city of Chengdu in Sichuan province, China. By topic Religion Ansgar is appointed missionary to Sweden by Louis the Pious, at the request of… (More on 829)