855
year
Year 855 (DCCCLV) was a common year starting on Tuesday of the Julian calendar.
Events
By place
Byzantine Empire
November 20 – Theoktistos, co-regent of the Empire on behalf of 15-year old Emperor Michael III, is murdered on the orders of Michael.
Central Europe
September 29 – Emperor Lothair I dies after a 15-year reign (co-ruling with his father Louis the Pious until 840). He divides the Middle Frankish Kingdom between his three sons in an agreement called the Treaty of Prüm—the eldest, Louis II, receives the northern half of Italy and the title of Holy Roman Emperor. The second, Lothair II, receives Lotharingia (the Low Countries and Upper Burgundy). The youngest, Charles, receives Lower Burgundy and Provence.
Britain
Spring – King Æthelwulf of Wessex decides to go on a pilgrimage to Rome, accompanied by his youngest son Alfred (age 6) and a large retinue. He divides the kingdom between his two eldest sons; Æthelbald receives the western part of Wessex, while Æthelberht becomes ruler over Kent, Surrey, Sussex and Essex.
Abbasid Caliphate
Caliph al-Mutawakkil sends an Abbasid army, led by the Turkic general Bugha al-Kabir, to suppress an uprising of rebellious Armenian nakharars. He subdues the country, and deports many Armenian nobles to the caliphal capital of Samarra.
Begin with the source’s own compact description: “855” is year. The dossier treats that line as a proposition to test through year, not as a finished interpretation.
Why this record matters
The phrase “year” supplies a clear boundary for inquiry. It also exposes the unanswered questions: who defined that boundary, when it became stable and which sources sit outside it.
Vocabulary and entity names are the principal evidence signals here, because they determine the precision of every later search. The source revision retrieved here is dated Apr 20, 2026. The linked authority identifier is Q25073. None of the 0 selected statements returned an explicit reference.
Overview language is designed for orientation and should not be treated as a substitute for the evidence cited beneath it. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
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This entry incorporates text from “855” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.