April 5, 838: Caliph al-Mu' tasim launches his campaign on Asia Minor
Early June, 838: Emperor Theophilos departs from Constantinople
June 19, 838: A contingent of the Arab expeditionary force under Ashinas enters western Cappadocia
June 21, 838: The bulk of the Arab army under caliph al-Mu' tasim enters western
Cappadocia
July 22, 838: Battle at the plain of Dazimon. The Byzantines are defeated by the Arabs