|Covid-19|Emperor Lothair I meets his (half brothers (Louis the German and Charles the Bald) in Attigny (Ardennes) for the third time, to continue the system of "con-fraternal government".
The Viking chieftains Rorik and Godfrid Haraldsson return to Demark, to gain power after the death of King Horik I. During a civil war, they are forced to go back to Friesland.
The German city of Ulm is first mentioned in a document by Louis the German.
King Æthelwulf of Wessex sends his two youngest sons, Alfred and Æthelred, on a pilgrimage to Rome.
King Æthelweard of East Anglia dies, and is succeeded by his 14-year-old son Edmund ("the Martyr").
King Cyngen of Powys makes the first pilgrimage to Rome of a Welsh ruler.
Viking chieftain Ubba winters in Milford Haven (Wales) with 23 ships.
Eardulf becomes bishop of Lindisfarne, after the death of Eanbert.
Al-Mu'tadid, Muslim caliph (or 861)
Cadell ap Rhodri, king of Seisyllwg (d. 909)
Cui Yin, chancellor of the Tang Dynasty (d. 904)
Muhammad ibn Zakariyā al-Rāzī, Persian philosopher (d. 925)
Theobald the Elder, Frankish nobleman (d. 942)
Abu Thawr, Muslim scholar (b. 764)
Æthelweard, king of East Anglia
Eanbert, bishop of Lindisfarne
Horik I, Viking king of Denmark
Luidger, bishop of Utrecht (approximate date)
Osburh, queen of Wessex (approximate date)
Sahnun ibn Sa'id, Muslim jurist (or 855)
Túathal mac Máele-Brigte, king of Leinster
Wang Yuankui, Chinese general (b. 812)
Wigmund, archbishop of York
Year 854 (DCCCLIV) was a common year starting on Monday (link will display the full calendar) of the Julian calendar.