Year by year · 9th century

866 CE

866 CE in world history: 2 events, 5 deaths, 1 state founded and 1 that came to an end. 354 recorded states existed that year.

Events

  1. 26 May

    Michael III crowns Basil I as Byzantine co-emperor

    Emperor Michael III crowned his favourite Basil, born to a peasant family, Byzantine co-emperor. Fearing a loss of influence, Basil had Michael assassinated the next year, becoming sole ruler and founding the Macedonian dynasty.

    Basil I

  2. 2 July

    A Breton-Viking army defeats the Franks at Brissarthe

    A joint Breton-Viking army defeated the West Franks near Brissarthe in Neustria, killing the Neustrian margrave Robert the Strong and Ranulf I, Duke of Aquitaine. Robert's sons Odo and Robert I both later became kings of West Francia.

    Robert the StrongVikingsBretons
ProfileState259 states with a known seat in 866 CEOpen the atlas at 866 CE →

Died in 866 CE 5

States founded 1

States that came to an end 1

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APA
The Epoch Institute. (2026). 866 CE. In The Epoch Institute, Year by Year. https://the-epoch-institute.org/years/866
MLA
“866 CE.” The Epoch Institute, Year by Year, The Epoch Institute, 2026, https://the-epoch-institute.org/years/866. Accessed .
Chicago
The Epoch Institute. “866 CE.” The Epoch Institute, Year by Year. 2026. https://the-epoch-institute.org/years/866.
Harvard
The Epoch Institute (2026) ‘866 CE’, The Epoch Institute, Year by Year. Available at: https://the-epoch-institute.org/years/866 (Accessed: ).