EuropeFebruary 1 – King Ramiro I dies in his palace at Santa María del Naranco (near Oviedo), after a 8-year reign. He is succeeded by his son Ordoño I, as ruler of Asturias.
Danish Viking raiders, led by King Rorik, conquer Dorestad and Utrecht (modern-day Netherlands). Emperor Lothair I recognizes him as ruler of most of Friesland.
King Louis II, the eldest son of Lothair I, is crowned joint emperor by Pope Leo IV at Rome, and becomes co-ruler of the Middle Frankish Kingdom.
BritainKing Kenneth I (also called Kenneth MacAlpin) of Alba (modern Scotland) invades Northern Northumbria during the period of 850–858, burning Dunbar and Melrose.
The Pillar of Eliseg is erected by King Cyngen ap Cadell of Powys (Wales), as a memorial to his great-grandfather Elisedd ap Gwylog (or Eliseg) (approximate date).
JapanMay 6 – Emperor Ninmyō dies after a 17-year reign. He is succeeded by his son Montoku, as the 55th emperor of Japan.
IndiaIt is hypothesized that sometime around 850 a group of Buddhist pilgrims travelling through a valley near Roopkund (modern India) were killed when caught out in the open in a sudden hailstorm. Their remains were discovered in 1942.
MesoamericaUxmal becomes the capital of a large state in the Puuk hills region of northern Yucatán (modern Mexico). The city is connected by causeways (sakbe) to other important Puuk sites, such as K'abah, Sayil, and Labna (approximate date).
Food and DrinkCoffee is discovered (according to legend) by the Ethiopian goatherder Kaldi in East Africa, who notices that his goats become energetic after chewing the red berries from certain wild bushes (approximate date).
ReligionApril 22 – Gunther becomes archbishop of Cologne (modern Germany).
June 18 – Perfecto, a Christian priest in Muslim Córdoba, is executed (beheaded) after he refuses to retract numerous insults he made about the prophet Muhammad.
AsiaBagrat II Bagratuni, Armenian prince and leader of a rebellion against the Abbasid Caliphate, is captured by the Abbasid army, and brought to the caliphal capital of Samarra.
BritainDanish Viking raiders enter the Thames Estuary, and plunder Canterbury and London. They land at Wembury near Plymouth, but are defeated by Anglo-Saxon forces led by King Ethelwulf of Wessex. His eldest son Æthelstan of Kent, accompanied by Ealdorman Ealhhere, attacks a Viking fleet off the coast at Sandwich, and captures nine of the enemy vessels while the remainder flees.
ChinaSuleiman al-Tajir, Muslim merchant and traveller, visits China during the Tang Dynasty. He observes the manufacturing of Chinese porcelain at Guangzhou, and writes of his admiration for its transparent quality. Suleiman also describes the mosque at Guangzhou, its granaries, its local government administration, some of its written records, and the treatment of travellers, along with the use of ceramics, rice wine, and tea (approximate date).
EuropeAugust 22 – Battle of Jengland: Duke Erispoe takes command of the Breton forces after his father Nominoe, king of Brittany, dies. He continues an offensive against the Franks in alliance with Lambert II of Nantes. In Ille-et-Vilaine near Grand-Fougeray (Brittany), Erispoe defeats a Frankish-Saxon army (4,000 men) led by King Charles the Bald.
Treaty of Angers: Charles the Bald meets Erispoe in Angers, and acknowledges him as "king of Brittany". He recognizes the authority of Breton rule over the areas around Nantes, Rennes and Pays de Retz, which become part of the Breton March, a border zone. Erispoe takes the oath to Charles as king of the West Frankish Kingdom (but not an hommage lige which would be an allegiance). To mark the sovereignty of the Breton state, the future Dukes of Brittany are crowned as "Duke, king in their lands".
September – King Pepin II of Aquitaine is captured by the forces of Count Sans II Sancion, and handed over to Charles the Bald. He is detained in the monastery of Saint Medard in Soissons.
Emperor Lothair I meets with his (half) brothers Louis the German and Charles the Bald in Meerssen (modern-day Netherlands), to continue the system of "con-fraternal government".
King Íñigo Arista of Pamplona dies after a 27-year reign. He is succeeded by his son García Íñiguez, as king of Pamplona (later Navarra).
ReligionThe Great Mosque of Samarra (modern Iraq) is completed during the reign of Caliph Al-Mutawakkil.
EuropeMarch 4 – Trpimir I, duke (knez) of Croatia, and founder of the Trpimirović dynasty, issues a first state document in Bijaći of all Slavonic peoples. In this Latin document Trpimir refers to himself as the "duke of the Croats" (dux Chroatorum), and to his country as the "state of the Croats" (regnum Chroatorum).
Presian I, ruler (khan) of the Bulgarian Empire, dies after a 23-year reign in which the Bulgarians have expanded into Upper Macedonia and Serbia. He is succeeded by his son Boris I, as monarch of Bulgaria.
Emperor Lothair I and his (half) brother Charles the Bald join forces to remove the Vikings from the island of Oscelles, in the River Seine. After this has failed, Charles again pays them tribute (Danegeld).
BritainA Viking fleet of 350 vessels enters the Thames Estuary before turning north, and engages the Mercian forces under King Beorhtwulf. The Mercians are defeated, and retreat to their settlements. The Vikings then turn south and cross the river somewhere in Surrey; there they are slaughtered by a West Saxon army, led by King Æthelwulf and his son Aethelbald, at Oak Field (Aclea).
King Æthelstan, the eldest son of Æthelwulf, is killed by a Viking raiding party. He is succeeded by his brother Æthelberht, who becomes sub-king of Kent, Essex, Surrey and Sussex (approximate date).
Beorhtwulf dies after a 12-year reign, and is succeeded by his son Burgred as king of Mercia.
Al-AndalusAbd al-Rahman II, Umayyad emir of Córdoba, dies after a 30-year reign in which he has made additions to the Mosque–Cathedral at Córdoba. He is succeeded by his son Muhammad I, who will put down several revolts of the Muladi and Mozarabs in Muslim controlled areas in al-Andalus (modern Spain).
AviationAbbas ibn Firnas, Muslim physician and inventor, makes a first recorded tower jump in Córdoba. He wraps himself with vulture feathers and attaches two wings to his arms. The alleged attempt to fly is unsuccessful, but the garment slows his fall enough that he only sustains minor injuries.
ReligionGandersheim Abbey in Lower Saxony (modern Germany) is founded by Duke Liudolf of Saxony.
Byzantine EmpireMay 22 – A Byzantine fleet (85 ships and 5,000 men) sacks and destroys the port city of Damietta, located on the Nile Delta in Egypt. A large quantity of weapons and supplies intended for the Emirate of Crete are captured.
EuropeViking marauders in Gaul sail eastward from Nantes without opposition, and reach Tours. The monasteries at Saint-Florent-le-Vieil and Marmoutier are ravaged.
King Charles the Bald bribes Boris I, ruler (khan) of the Bulgarian Empire, to form an alliance against his brother Louis the German, with Rastislav of Moravia.
Gauzbert, count of Maine, is killed during an ambush by citizens of Nantes, in revenge for the death of Lambert II.
BritainKing Burgred of Mercia appeals to Æthelwulf, king of the West Saxons, for help against the rebellious Welsh king Rhodri the Great. Æthelwulf agrees to send help, and Wales is subdued as far north as Anglesey.
Burgred (who inherited his crown last year) marries Æthelwulf's daughter Æthelswith, during a ceremony at the royal estate at Chippenham.
ChinaTuan Ch'eng-Shih, Chinese author and scholar during the Tang Dynasty, publishes Miscellaneous Offerings from Yu-yang.
ReligionThe Fraumünster Church in Zürich (modern Switzerland) is founded by Louis the German.
EuropeEmperor 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.
BritainKing 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.
ReligionEardulf becomes bishop of Lindisfarne, after the death of Eanbert.
EuropeSeptember 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.
BritainSpring – 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 CaliphateCaliph al-Mutawakkil sends a 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.
ReligionJuly 17 – Pope Leo IV dies after a 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 Cyrill and Methodius.
Byzantine EmpireMarch 15 – Emperor Michael III overthrows the regency of his mother Theodora and the logothete Theoktistos. He appoints his uncle Bardas as the de facto regent and co-ruler of the Byzantine Empire.
EuropeKing Charles the Bald cedes the county of Maine to Erispoe, ruler (duke) of Brittany—this in return for an alliance against the Vikings.
King Ordoño I of Asturias is said to have begun the repopulation of the town of León in the northwest of Spain (approximate date).
BritainOctober 1 – King Æthelwulf of Wessex marries the 12- or 13-year-old Judith, daughter of Charles the Bald, at Verberie (Northern France). She is crowned queen and anointed by Hincmar, archbishop of Reims. The marriage is a diplomatic alliance between Wessex and the West Frankish Kingdom.
Winter – Æthelwulf returns to Wessex to face a revolt by his eldest son Æthelbald, who usurps the throne. Æthelwulf agrees to give up the western part of his kingdom, in order to avoid a civil war. He keeps control over Sussex, Surrey, Essex and Kent, over which Prince Æthelberht has presided.
GeologyNovember – An earthquake in Corinth in Greece kills an estimated 45,000 people (approximate date).
December 22 – Another earthquake strikes Damghan (modern Iran), killing an estimated 200,000 people.
Byzantine EmpireEmperor Michael III, under the influence of his uncle Bardas, banishes his mother Theodora to the Gastria Monastery. Bardas, the de facto regent, becomes the most powerful person in the Byzantine Empire.
EuropeNovember – Erispoe, ruler (duke) of Brittany, is assassinated by his cousin Salomon and followers, in the church at Talensac. King Charles the Bald acknowledges Salomon as the rightful 'king' of Brittany.
A Danish Viking fleet raids the cities of Dorestad, Paris and Orléans. Others sail up the Oise River, ravaging Beauvais and the abbey of Saint-Germer-de-Fly (approximate date).
Viking chieftain Rorik, with the agreement of King Lothair II, leaves Dorestad with a fleet and forces his rival Horik II to recognise him as ruler over Denmark (approximate date).
MedicineThe first recorded major outbreak of ergotism kills thousands of people in the Rhine Valley. They have eaten bread made from rye infected with the ergot fungus parasite Claviceps purpurea (approximate date).
EuropeSummer – King Louis the German, summoned by the diseffected Frankish nobles, invades the West Frankish Kingdom and secures Aquitaine for his nephew Pepin II ("the Younger"). King Charles the Bald flees to Burgundy; he is saved by the help of the bishops, and by the fidelity of the family of the Welfs, who are related to Judith (second wife of former emperor Louis the Pious).
Viking raiders, led by Björn Ironside, set fire to the earliest church on the site of Chartres Cathedral. Charles the Bald pays him tribute (Danegeld) to save Verberie (Northern France).
BritainJanuary 13 – King Æthelwulf of Wessex dies after an 18-year reign, and is succeeded by his eldest son Æthelbald. He marries his father's young widow Judith (daughter of Charles the Bald), and becomes sole ruler of Wessex. His brother, Æthelberht, is left to rule Kent and the south-east of England.
February 13 – King Kenneth I (Cináed mac Ailpín), king of the Scots, dies after a 15-year reign in which he has been crowned at Scone, and united the various parts of Scotland with his native Dál Riata. His 46-year-old brother succeeds as Donald I, king of Alba.
AsiaOctober 7 – Emperor Montoku dies after a 8-year reign. He is succeeded by his 8-year-old son Seiwa as the 56th emperor of Japan, with Fujiwara no Yoshifusa (Seiwa's grandfather) governing as regent and great minister of the Council of State.
An enormous flood along the Grand Canal inundates thousands of acres of farmland and kills tens of thousands of people in the North China Plain.
ReligionApril 17 – Pope Benedict III dies after a 3-year reign, in which he has intervened in a political conflict between the sons of Emperor Lothair I. He is succeeded by Nicholas I, as the 105th pope of Rome.
Synod of Quierzy: The bishops remain loyal to Charles the Bald during the invasion of his dominions by Louis the German. They address a conciliatory letter to Louis the German, which includes the False Decretals.
October 23 – Ignatios I, patriarch of Constantinople, is imprisoned by orders of Emperor Michael III, and replaced by the layman Photius I.
EuropeJanuary 15 – Battle of St. Quentin: Frankish forces led by Humfrid defeat King Louis the German at Saint-Quentin (Northern France). Humfrid is enfeoffed with the County of Autun, and appointed Margrave of Burgundy by King Charles the Bald.
Summer – The Viking chieftains Hastein and Björn Ironside (a son of Ragnar Lodbrok) begin an expedition, and sail from the Loire River with a fleet of 62 ships, to raid cities and monasteries in the Mediterranean Sea.
Viking raiders invade the Kingdom of Pamplona (Western Pyrenees), and capture King García Íñiguez I, somewhere in the Andalusian heartland. They extort a ransom, rising to around 70,000 gold dinars.
The Russian city of Novgorod is first mentioned in the Sofia chronicles.
Winter - The weather is so severe that the Adriatic Sea freezes, and Italy is covered in snow for 100 days.
Iberian PeninsulaBattle of Albelda: King Ordoño I of Asturias, and his ally García Íñiguez I, defeat the Muslims under Musa ibn Musa al-Qasawi at Albelda.
Viking raiders burn the mosques of Seville and Algesiras in al-Andalus (modern Spain).
AfricaThe University of Al Karaouine is founded in Fes (modern Morocco), by Fatima al-Fihri (recognized by the Guinness Book of World Records as the oldest university in the world).
ChinaSeptember 7 – Emperor Xuān Zong (Li Yi) dies after a 13-year reign. He is succeeded by his eldest son Yi Zong, as ruler of the Tang Dynasty.
Charles the Bald
Louis the German
Ethelwulf of Wessex
Kenneth I of Scotland
Halfdan the Black
Abu Ja'far Muhammad ibn Musa al-Khwarizmi