Editing 866 (section)

== Events ==
<onlyinclude>

=== By place ===

==== Byzantine Empire ====
* [[April 21]] &ndash; [[Bardas]], the regent of the [[Byzantine Empire]], is murdered by [[Basil I|Basil the Macedonian]] at [[Miletus]], while conducting a large-scale expedition against the [[Saracen]] stronghold of [[Emirate of Crete|Crete]].

* [[May 26]] &ndash; Basil the Macedonian is crowned co-emperor of the [[Byzantine Empire]], and is [[Adoption|adopted]] by the much younger Michael III.

==== Europe ====
* [[May 27]] &ndash; King [[Ordoño I of Asturias|Ordoño I]], ruler of the [[Kingdom of Asturias]], dies after a 16-year reign. He is succeeded by his son, [[Alfonso III of Asturias|Alfonso III]], who later is referred to as  "Alfonso the Great".
* [[July 2]] &ndash; [[Battle of Brissarthe]]: Frankish forces, led by [[Robert the Strong]], are defeated by a joint [[Bretons|Breton]]-[[Vikings|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 [[Kingdom of Northumbria|Northumbria]]. The Northumbrians are preoccupied with a [[civil war]], and the [[Denmark|Danes]] enter [[York]] unopposed.<ref>John Haywood (1995). ''Historical Atlas of the Vikings'', p. 62. Penguin Books: {{ISBN|978-0-140-51328-8}}</ref>

==== Abbasid Caliphate ====
* [[October 17]] &ndash; 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.<ref>History of the Arabs by Philip K. Hitti.</ref>
* The [[Kharijite Rebellion (866–896)|Kharijite revolt]] against the [[Abbasid Caliphate]] begins in [[Upper Mesopotamia|Al-Jazira (Upper Mesopotamia)]], which will last for 30 years.

==== Japan ====
* [[Fujiwara no Yoshifusa]] becomes [[regent]] (''[[Sesshō and Kampaku|sesshō]]'') to assist the child emperor [[Emperor Seiwa|Seiwa]], starting the [[Fujiwara clan|Fujiwara]] regency.

=== By topic ===

==== Religion ====
* [[Boris I of Bulgaria|Boris I]], ruler (''[[knyaz]]'') of the [[First Bulgarian Empire|Bulgarian Empire]], sends a [[diplomatic mission]], led by the Bulgarian nobleman [[Peter (diplomat)|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"<ref>{{cite news|title=Beyond the Trivia - Fish Fridays|url=https://krcgtv.com/features/beyond-the-trivia/beyond-the-trivia-fish-fridays#:~:text=It%20was%20Pope%20Nicolas%20I,in%20memory%20of%20Christ's%20death.|first=Preston|last=Dick|publisher=[[KRCG]]|date=2023-02-24|access-date=2023-03-01}}</ref> of warm-blooded animals on Wednesdays and Fridays.<ref>{{cite web|title=How Did the Roman Catholic Tradition of Eating Fish on Fridays Begin?|date=March 15, 2019 |url=https://kofc5357.org/2019/03/15/how-did-the-roman-catholic-tradition-of-eating-fish-on-fridays-begin/|access-date=2023-03-01}}</ref>
* Pope Nicholas I forbids the use of [[torture]] in prosecutions for [[witchcraft]] (approximate date).</onlyinclude>