866 CE
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. Basil the Macedonian is crowned co-emperor of the Byzantine Empire, and is adopted by the much younger Michael III. 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.
Geopolitics & Diplomacy
Conflict & Security
- July 2 – Battle of Brissarthe: Frankish forces, led by Robert the Strong, are defeated by a joint Breton-Viking army.source
- The Kharijite revolt against the Abbasid Caliphate begins in Al-Jazira (Upper Mesopotamia), which will last for 30 years.source
- Louis II, Holy Roman Emperor, defeats the Saracen invaders who are ravaging southern Italy.source
- An army in Lucera is assembled by orders of Louis II in preparation for an attack on the Emirate of Bari.source
Exploration & Expansion
- 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.source
Religion & Belief
- 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.source
- Pope Nicholas I forbids the use of torture in prosecutions for witchcraft (approximate date).source
- Pope Nicholas I orders that all Catholics should abstain from eating the "flesh, blood, or marrow" of warm-blooded animals on Wednesdays and Fridays.source
Crime & Justice
- 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.source
Culture & Society
- May 26 – Basil the Macedonian is crowned co-emperor of the Byzantine Empire, and is adopted by the much younger Michael III.source
Births
Deaths
- April 21 – Bardas, Byzantine chief minister and regentsource
- May 27 – Ordoño I, king of Asturiassource
- 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".source
- June 21 – Rodulf, Frankish archbishopsource
- July 2 – Robert the Strong, Frankish noblemansource
- July 16 – Irmgard, Frankish abbesssource
- October 17 – Al-Musta'in, Abbasid caliphsource
- Linji Yixuan, Chinese monk and founder of the Linji schoolsource
- Hungerus Frisus, bishop of Utrechtsource
- Ranulf I, Frankish nobleman (b. 820)source
- Charles the Child, king of Aquitainesource
- Yahya ibn Yahya, Idrisid emir of Moroccosource
- Adelaide of Tours, Frankish noblewomansource
- Wang Shaoyi, general of the Tang Dynastysource