855

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. He divides the Middle Frankish Kingdom between his three sons in an agreement called the Treaty of Prüm—the eldest, Louis II, [Holy Roman Emperor|Louis II], receives the northern half of Italy and the title of Holy Roman Emperor. The second, Lothair II, receives Lotharingia. 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 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.

  By topic

Religion

• July 17 - Pope Leo IV dies after an 8-year reign, and is succeeded by Benedict III as the 104th pope of Rome. Anastasius is made anti-pope by Lothair I.
• Æthelwulf grants churches in Wessex the right to receive tithes. He gives one-tenth of his lands to the Church.
• The Slavic alphabet is created by Saints Cyril and Methodius.