King Wigstan of Mercia, grandson of former ruler Wiglaf (see 839), declines his kingship in preference of the religious life. He asks his widowed mother, Princess Ælfflæd, to act as regent. A nobleman of the line of the late king Beornred, named Berhtric, wishes to marry her but he is a relative. Wigstan refuses the match, and is murdered by followers of Berhtric at Wistow. He is buried at Repton Abbey, and later revered as a saint. The Mercian throne is seized by Berhtric's father, Beorhtwulf.[1]: 238–239
Emperor Wenzong (Li Ang) dies after a 13-year reign, in which he has failed to break the power of his palace eunuchs. He is succeeded by his brother Wu Zong, as Chinese ruler of the Tang dynasty.
The town of Dyflin (meaning "Black Pool") or Dublin (modern Ireland) is founded by Norwegian Vikings, on the south bank of the River Liffey. The settlement is fortified with a ditch and an earth rampart, with a wooden palisade on top. The Norsemen establish a wool weaving industry, and there is also a slave trade. An artificial hill is erected, where the nobility meets to make laws and discuss policy.
Venice sends a fleet of 60 galleys (each carrying 200 men) to assist the Byzantines in driving the Arabs from Crotone, but the attack fails. Muslim troops conquer the city of Brindisi (approximate date).[7]
In the Chinese capital of Chang'an, the West Market (and East Market) are closed every night one hour and three quarters before dusk (by government order); the curfew is signaled by the sound of 300 beats to a loud gong. After the official markets have been closed for the night, small night markets in residential areas thrive with plenty of customers, despite government efforts to shut them down. With the decline of the government's authority (by mid 9th century), this edict (like many others) is largely ignored, as urban dwellers keep attending the night markets regardless.
Summer – Viking raiders attack Nantes, located on the River Loire; they kill the town's bishop along with many of the clergy, and murder men, women and children. They plunder the western parts of Aquitaine and reach an island north of the mouth of the River Garonne, near what later will be La Rochelle. There the Vikings bring materials from the mainland and build houses to spend the winter.
Summer – A Byzantine expedition, led by Theoktistos, conquers Crete from the Saracens. After initial success, he is forced to abandon his army, due to political intrigues in Constantinople. The troops are left behind and slaughtered by the Arabs.[11][12]
In the Chinese capital of Chang'an, a large fire consumes 4,000 homes, warehouses and other buildings in the East Market, yet the rest of the city is at a safe distance from the blaze which is largely quarantined in East Central Chang'an, thanks to the large width of roads in Chang'an that produce fire breaks.
King Æthelred II of Northumbria is expelled from his kingdom by Rædwulf, who takes the throne. Rædwulf is later killed in battle against the Vikings, along with many of his noblemen. Æthelred returns and claims his right to rule.
King Merfyn Frych dies after a 24-year reign. He is succeeded by his son Rhodri Mawr ("the Great"), who thus becomes ruler of Gwynedd (Wales).
March 28 or 29 (Easter) – Siege of Paris: Viking forces under the Norse chieftain Ragnar Lodbrok enter the River Seine, with a fleet of 120 longships (5,000 men). They pass through the city of Rouen and plunder the countryside. King Charles the Bald assembles an army and sends it to protect Paris, the capital of the West Frankish Kingdom. Ragnar routs the enemy forces, and hangs 111 of their prisoners in honour of Odin.[21] Charles — to keep them from plundering his kingdom — pays a large tribute of 7,000 livres (pounds) of silver or gold, in exchange for their leaving.[22] The Vikings also sack the cities of Hamburg and Melun.
Frankish forces led by Louis the German invade Moravia. They encounter little resistance, and depose King Mojmir I from the throne.[24] His relative, Rastislav, is set up as the new client ruler.
Muslim forces attempt to raid Rome but only pillage the countryside around the city before being beaten back by Duke Guy I of Spoleto. In the aftermath, Pope Leo IV starts walling the area around the Vatican hill, creating the Leonine City.
DanishVikings land in the Breton March (western part of Gaul). Duke Nominoe of Brittany fails to withstand them in battle, but succeeds in buying them off with gifts and persuading them to leave (approximate date).
Emperor Lothair I, and his (half) brothers Louis the German and Charles the Bald, meet in Koblenz to continue the system of "con-fraternal government".
The Saracens conquer Ragusa (Sicily), after its Byzantine garrison is forced by severe famine to surrender. The city and its castle are razed to the ground.[27]
Britain
The armies of Brycheiniog and Gwent clash in the battle of Ffinnant (Wales). King Ithel of Gwent is killed in the fighting (approximate date).
Summer – Battle of Ostia: A Saracen Arab fleet from Sardinia sets sail towards Rome. In response, Pope Leo IV forms a coalition of maritime Italian cities, including Naples, Amalfi and Gaeta, led by Admiral Caesar — which is assembled off the re-fortified port of Ostia — and repels the Saracen marauders. Their navy is scattered, resulting in many sunken vessels. Rome is saved from plunder and the expansion of the Aghlabids.[29]
In the Chinese capital city of Chang'an, an imperial prince is impeached during the Tang Dynasty from his position by officials at court, for erecting a building that obstructs a street in the northwesternmost ward in South Central Chang'an.
January – Michael III, Byzantine emperor (d. 867) This date of birth is generally held as uncertain; though January 840 is the most probable, 839 is also possible.
August 16 – Death of Qaratis also known as Umm Harun, was the mother of Abbasid caliph al-Wathiq (r. 842–847). She died during her Hajj pilgrimage journey.
^Eric Joseph, Struggle for Empire, p. 103. Cornell University, 2006. ISBN0-8014-3890-X. Joseph states this number, given by Agnellus of Ravenna, is probably exaggerated.
^Rucquoi, Adeline (1993). Histoire médiévale de la Péninsule ibérique. Paris: Seuil. p. 85. ISBN2-02-012935-3.
^AF a. 844: Karolus Aquitaniam, quasi ad partem regni sui iure pertinentem, affectans ... ("Charles wanted Aquitaine, which belonged by right to a part of his kingdom").