866

By place

Byzantine Empire

• April 21 , Bardas, the regent of the Byzantine Empire, is murdered by Basil the Macedonian at Miletus, while conducting a large-scale expedition against the Saracen stronghold of Crete.

• May 26 , Basil the Macedonian is crowned co-emperor of the Byzantine Empire, and is adopted by the much younger Michael III.

Europe

• May 27 , King Ordoño I, ruler of the Kingdom of Asturias, dies after a 16-year reign. He is succeeded by his son, Alfonso III, who later is referred to as "Alfonso the Great".
• July 2 , Battle of Brissarthe: Frankish forces, led by Robert the Strong, are defeated by a joint Breton-Viking army.
• Louis II, Holy Roman Emperor, defeats the Saracen invaders who are ravaging southern Italy.

Britain

• The Great Heathen Army of the Vikings rides north to Northumbria. The Northumbrians are preoccupied with a civil war, and the Danes enter York unopposed.

Italy

• An army in Lucera is assembled by orders of Louis II in preparation for an attack on the Emirate of Bari.

Abbasid Caliphate

• October 17 , Caliph al-Musta'in is put to death, after a 4-year reign. He is succeeded by al-Mu'tazz, who becomes the youngest Abbasid caliph to assume power.
• The Kharijite revolt against the Abbasid Caliphate begins in Al-Jazira (Upper Mesopotamia), which will last for 30 years.

Japan

• Fujiwara no Yoshifusa becomes regent (sesshō) to assist the child emperor Seiwa, starting the Fujiwara regency.

By topic

Religion

• Boris I, ruler (knyaz) of the Bulgarian Empire, sends a diplomatic mission, led by the Bulgarian nobleman Peter, to Rome, in an effort to renew ties with the West.
• Pope Nicholas I orders that all Catholics should abstain from eating the "flesh, blood, or marrow" of warm-blooded animals on Wednesdays and Fridays.
• Pope Nicholas I forbids the use of torture in prosecutions for witchcraft (approximate date).

• June 10 , Uda, emperor of Japan (d. 931)
• September 19 , Leo VI, Byzantine emperor (d. 912)
• Carloman II, king of the West Frankish Kingdom (approximate date)
• Robert I, king of the West Frankish Kingdom (d. 923)
• Yao Yi, chancellor of Later Tang (d. 940)

• April 21 , Bardas, Byzantine chief minister and regent
• May 27 , Ordoño I, king of Asturias
• June 21 , Rodulf, Frankish archbishop
• July 2 , Robert the Strong, Frankish nobleman
• July 16 , Irmgard, Frankish abbess
• October 17 , Al-Musta'in, Abbasid caliph
• Adelaide of Tours, Frankish noblewoman
• Al-Mu'ayyad, Abbasid prince
• Charles the Child, king of Aquitaine
• Eberhard, duke of Friuli
• Emenon, Frankish nobleman
• Hungerus Frisus, bishop of Utrecht
• Linji Yixuan, Chinese monk and founder of the Linji school
• Liudolf, duke of Saxony
• Ranulf I, Frankish nobleman (b. 820)
• Robert, Frankish nobleman (b. 834)
• Rudolph, Frankish nobleman
• Wang Shaoyi, general of the Tang Dynasty
• Yahya ibn Yahya, Idrisid emir of Morocco