Dentō Daihōshi Saichō dies at the age of 54. The record notes that at the end of the Enryaku era he went to Tang, studied Tiantai at Taizhou, and on his return spread it widely. (Nihon Kōki (Later Chronicles of Japan) 日本後紀 卷30)
The siege of Shenzhou is not lifted, so the court makes Wang Tingzhu Military Commissioner of Chengde. (Zizhi Tongjian (Comprehensive Mirror) 資治通鑑 卷242)
Wang Zhixing's light troops raid Haozhou, and Prefect Hou Hongdu abandons the city and flees to Shouzhou. (Zizhi Tongjian (Comprehensive Mirror) 資治通鑑 卷242)
Korean Peninsula (2)
Kim Heonchang, governor of Ungcheon-ju, rebelled, citing that his father Kim Juwon had not become king; he proclaimed the state name Jangan and the era name Gyeongun. (Samguk Sagi (History of the Three Kingdoms) 卷10 憲德王 14年)
The punitive army reached Ungjin and won a great battle; Kim Heonchang entered his fortress, held out, and took his own life. (Samguk Sagi (History of the Three Kingdoms) 卷10 憲德王 14年)
Japan (1)
A banquet is held at the Hōraku Hall for officials of fifth rank and above and for foreign guests; the Balhae envoy Wang Wenju and others play dagiu (polo), and 200 tun of cotton is offered as a prize. (Nihon Kōki (Later Chronicles of Japan) 日本後紀 卷30)
Southern Europe (1)
When the army from Italy enters Pannonia, Riudewit abandons the city of Siscia and flees to the Sorbs, who occupy most of Dalmatia; he tricks and kills one of their chiefs, takes the city, and promises to go to the emperor (Royal Frankish Annals ARF a.822, Kurze 1895 p.158)
Western Europe (2)
At the August assembly at Attigny, the emperor publicly confesses before all the people that he forced his brothers to be shaved, and his matters concerning his nephew Bernard and Adalhard (Royal Frankish Annals ARF a.822, Kurze 1895 p.158)
After the autumn hunt the emperor crosses the Rhine and winters at Frankfurt, holding an assembly, and receives envoys from the Eastern Slavs (Abodrites, Sorbs, Wilzi, Bohemia, Moravia), the Avars of Pannonia, and the Northmen (sons of Heriold and Godofrid) (Royal Frankish Annals ARF a.822, Kurze 1895 p.159)