Editing 831 (section)

== Events ==
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=== By place ===
==== Abbasid Empire and Byzantine Empire ====
* [[Byzantine–Arab wars (780–1180)#Period of 780–842|Byzantine–Arab War]]: Emperor [[Theophilos (emperor)|Theophilos]] invades the [[Abbasid Caliphate|Abbasid]] dominions, and reaches the [[Euphrates|Euphrates River]] in north-eastern [[Syria]]. He captures and sacks the city of [[Tarsus, Mersin|Tarsus]], but is defeated in [[Cappadocia]].
* Summer &ndash; [[Arab Muslims|Muslim Arabs]] under Caliph [[Al-Ma'mun]] launch an invasion into [[Anatolia]] (modern [[Turkey]]), and capture a number of [[Byzantine Empire|Byzantine]] forts. [[Heraclea Cybistra]] and [[Tyana]] fall to the Arabs.   
* Fall &ndash; Muslim Arabs reinvade [[Sicily]], and lay [[siege]] to [[Palermo]]. Symeon, Byzantine commander of the imperial bodyguard (''[[spatharios]]''), surrenders the city in exchange for a safe departure.

==== Europe ====
* Emperor [[Louis the Pious]] is reinstated as sole ruler of the [[Francia|Frankish Empire]]. He promises his sons [[Pepin I of Aquitaine|Pepin I]] and [[Louis the German]] a greater share of the [[inheritance]]. His eldest son [[Lothair I]] is [[pardon]]ed, but disgraced and banished to [[Italy]].
* [[February]] &ndash; Empress [[Judith of Bavaria (died 843)|Judith]] stands trial to "undergo the judgment of the [[Franks]]"<ref name="Nelson">Nelson, Janet L. The Annals of St-Bertin. Manchester: Manchester UP, 1991. Print.</ref> for an assembly arranged by Louis the Pious, and is exonerated.{{clarify|date=August 2022|was she on trial in an assembly or was it because Louis made an assembly she was blamed for?}}
* [[Omurtag of Bulgaria|Omurtag]], ruler (''[[Khan (title)|khan]]'') of the [[First Bulgarian Empire|Bulgarian Empire]], dies after a 17-year reign. He is succeeded by his youngest son [[Malamir of Bulgaria|Malamir]], because his older brother [[Enravota]] favours [[Christianity]].
* [[Nominoe]], duke of [[Duchy of Brittany|Brittany]], is designated ''[[Missus dominicus|missus imperatoris]]'' (imperial [[Ambassador|emissary]]) by Louis the Pious, at [[Ingelheim am Rhein|Ingelheim]] (modern [[Germany]]).<ref>Smith, p. 83.</ref>

==== China ====
* An [[Uyghur people|Uyghur]] [[Turkic peoples|Turk]] sues the son of a Chinese general, who had failed to repay a debt of 11 million government-issued [[copper]] coins. Emperor [[Emperor Wenzong of Tang|Wenzong]] hears the news, and is so upset that he not only banishes the general, but attempts to ban all [[trade]] between Chinese and foreigners except for goods and [[livestock]]. This ban is unsuccessful, and trade with foreigners resumes, especially in maritime affairs overseas.

=== By topic ===
==== Religion ====
* Summer &ndash; [[Ansgar]], Frankish [[missionary]], founds the first [[Church (building)|church]] at [[Birka]] (modern [[Sweden]]).
* Ansgar is consecrated; he travels to [[Rome]] to receive the [[pallium]] from [[Pope Gregory IV]].
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