840s

Millennium
1st millennium
Centuries
8th century 9th century 10th century
Decades
820s 830s 840s 850s 860s
Years
840 841 842 843 844 845 846 847 848 849
Categories
Births Deaths Establishments Disestablishments
v t e

The 840s decade ran from January 1, 840, to December 31, 849.

• June 20 – Emperor Louis the Pious falls ill and dies at his hunting lodge, on an island in the Rhine, near his imperial palace at Ingelheim, while suppressing a revolt. His eldest son Lothair I succeeds him as Holy Roman Emperor, and tries to seize all the territories of the late Charlemagne. Charles the Bald, 17, becomes king of the Franks, and joins with his half-brother Louis the German, in resisting Lothair.
• Vikings from Norway capture Dublin, and establish a Norse kingdom in Ireland.

• 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}
• Vikings make permanent settlements with their first 'wintering over', located at Lough Neagh in Northern Ireland (approximate date).

• 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 Yenisei Kirghiz settle along the Yenisei River, and sack with a force of around 80,000 horsemen the Uyghur capital, Ordu-Baliq (driving the Uyghurs out of Mongolia). This ends the Uyghur Khaganate.^[2]
• The 840 Erzurum earthquake takes place in the city of Qaliqala (modern Erzurum).^[3]

• Nobis becomes bishop of St. David's, in the Welsh Kingdom of Dyfed (approximate date).

• June 25 – Battle of Fontenay: Frankish forces of Emperor Lothair I, and his nephew Pepin II of Aquitaine, are defeated by allied forces of King Louis the German, and his half-brother Charles the Bald, at Fontenoy (Eastern France), in a civil war among the three surviving sons of the former emperor Louis the Pious. A total of 40,000 men are killed, including the Frankish nobles Gerard of Auvergne and Ricwin of Nantes, fighting on the side of Charles.^[4]
• Summer – Vikings sail up the River Seine and devastate the city of Rouen in Normandy. They burn the Benedictine monastery of Jumièges Abbey; 68 captives are taken, and returned on payment of a ransom, by the monks of St. Denis.^[5]

• 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.

• Constantine Kontomytes, Byzantine general (strategos) of the Thracesian Theme, inflicts a severe defeat on the Cretan Saracens. He leads a Byzantine expeditionary force, to raid the monastic community near Mount Latros (modern Turkey).^[6]
• 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]

• A pro-Umayyad rebellion, led by al-Mubarqa in Palestine, breaks out against caliph al-Mu'tasim of the Abbasid Caliphate (ending in 842).^[8]

• 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.

• January 20 – Emperor Theophilos dies of dysentery at Constantinople, after a 12-year reign in which he expended much effort defending the eastern frontier against the invading Muslim Arabs. Theophilos is succeeded by his 2-year-old son Michael III, with his mother Theodora as regent and the 'temporary' sole ruler of the Byzantine Empire.^[9]
• February 19 – The Medieval Iconoclastic Controversy ends, as a council in Constantinople formally reinstates the veneration of icons in the churches.

• February 14 – Oaths of Strasbourg: King Louis the German, ruler of East Francia, and his half-brother Charles the Bald, ruler of West Francia, meet with their armies at Strasbourg. They agree to swear allegiance (recorded in vernacular languages) to each other, and to support each other against their brother Lothair I (nominal emperor of all the Frankish kingdoms and the Holy Roman Empire).^[10]
• March 20 – King Alfonso II of Asturias (Northern Spain) dies after a 50-year reign, in which he undertook numerous campaigns against the Muslim armies of the Umayyad Emirate of Córdoba, and allied himself with the late Charlemagne. The childless Alfonso chooses Ramiro I, son of former king Bermudo I, as his successor.

• Uurad of the Picts dies after a 3-year reign, and is succeeded by his son Bridei VI, who contests his power with rival groups, led by Bruide son of Fokel and Kenneth MacAlpin.
• Vikings attack the Irish monastery at Clonmacnoise from bases in Ireland.

• January 5 – Caliph Al-Mu'tasim dies at Samarra (modern Iraq), after an eight year reign. He is succeeded by his son Al-Wathiq, as ruler of the Abbasid Caliphate.

• May 24 – Battle of Blain: Breton forces under Erispoe, count of Vannes, defeat the Franks led by Renaud d'Herbauges, near the town of Messac, at the River Vilaine. This battle marks a Breton war between Charles the Bald and Nominoe, duke of Brittany.
• 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.
• August 10 – Treaty of Verdun: The Frankish Empire is divided into three kingdoms, between the three surviving sons of the late emperor Louis the Pious. King Louis the German receives the eastern portion (everything east of the River Rhine), called the Eastern Frankish Realm, which is the precursor to modern-day Germany. Emperor Lothair I receives the central portion (Low Countries, Alsace, Lorraine, Burgundy and the northern half of Italy), called the Central Frankish Realm. King Charles the Bald receives the western portion (everything west of the River Rhône), called the Western Frankish Realm, which later becomes France.

• King Kenneth MacAlpin (Cináed mac Ailpín) of the Scots also becomes king of the Picts; he is crowned (on the Stone of Destiny) as first monarch of the new nation of Scotland. The Alpin Dynasty of Scottish kings begins to reign.

• 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]
• Al-Andalus: The city of Zaragossa rises against the Umayyad Emirate of Córdoba in modern-day Spain.^[13]

• 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.

• March 11 – Feast of Orthodoxy – Official end of Iconoclasm: Empress Theodora II restores the veneration of icons in the Orthodox churches in the Byzantine Empire.^[14]
• Theodora II orders a persecution against the Paulicians throughout Anatolia; about 100,000 followers in the Byzantine theme of Armenia are massacred.^[15]

• Spring – Battle of Mauropotamos: A Byzantine expedition under Theoktistos is sent to Anatolia (modern Turkey), against the Muslim Arabs of the Abbasid Caliphate, who have raided the Byzantine themes of Cappadocia, Anatolikon, Boukellarion, and Opsikion. The Byzantines are defeated, and many of the officers defect to the Arabs.^[16]

• Viking raiders ascend the River Garonne as far as the city of Toulouse, and pillage the lands of Septimania. Part of the marauding Vikings invades Galicia (Northern Spain), where some perish in a storm at sea. After being defeated in Corunna, the Scandinavian raiders sack the Umayyad cities of Seville (see below), Niebla, Beja, and Lisbon.^[17]
• Summer – King Charles the Bald struggles against the repeated rebellions in Aquitaine, and against the Bretons in West Francia. He besieges Bernard I at the Battle of Toulouse, while Duke Nominoe raids into Maine, and plunders other Frankish territory.^[18]
• June 15 – Louis II, eldest son of Emperor Lothair I, is crowned king at Rome by Pope Sergius II, and becomes co-ruler of Middle Francia, and over Lombardy, Friuli, and Tuscany in Italy.
• September 25–November 11 or 17 – Viking raid on Seville (844): Vikings arrive in Seville by the Guadalquivir, taking the city on October 1 or 3 and pillaging it; but are expelled by forces of the Emirate of Córdoba.

• 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).

• January 25 – Pope Gregory IV dies after a 16-year reign, in which he has supported the Frankish policy of late emperor Louis the Pious, and established the observance of All Saints' Day. He is succeeded by Sergius II, as the 102nd pope of Rome. Sergius imprisons the antipope John VIII, and is elected by popular acclamation.

• Byzantine–Arab War: A prisoner exchange occurs between the Byzantine Empire and the Abbasid Caliphate, at the River Lamos in Cilicia (modern Turkey). The exchanges last for 10 days, and the Byzantines recover 4,600 prisoners.^[19][20]

• 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.
• November 22 – Battle of Ballon: Frankish forces (3,000 men) led by Charles the Bald are defeated by Nominoe, count of Vannes, near Redon, Ille-et-Vilaine. After the battle, Brittany becomes a regnum 'kingdom' within the Frankish Empire.
• Viking forces destroy Hamburg.

• Great Anti-Buddhist Persecution: Emperor Wu Zong begins the persecution of Buddhists and other foreign religions in China, such as Zoroastrianism, Nestorian Christianity and Manichaeism. More than 4,600 monasteries, 40,000 temples and numerous shrines are destroyed. More than 260,000 Buddhist monks and nuns are forced to return to secular life.
• March 6 – 42 captured Byzantine officials from Amorium are executed at Samarra, then the capital of the Abbasid Caliphate, after repeated failed attempts to convert them to Islam.

• John Scotus Eriugena, Irish theologian, travels to France and takes over the Palatine Academy in Paris, at the invitation of Charles the Bald (approximate date).

• Byzantine–Bulgarian War: The Bulgarians violate the peace treaty (see 815), and invade Macedonia along the River Struma. The cities of Serres and Philippi are devastated.^[23]

• Summer – Breton forces under Nominoe occupy the Frankish cities of Nantes and Rennes. He makes raids in Anjou and threatens Bayeux. King Charles the Bald recognizes him as duke of Brittany.
• Prince Pribina becomes a vassal of the Frankish Empire. King Louis the German grants him land near Lake Balaton (modern Hungary). He establishes Blatnohrad, capital of Balaton Principality.
• 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.
• The Mozarabs, Iberian Christians who live under Moorish rule, try to repopulate León in Al-Andalus (modern Spain). The city is recaptured by the Muslim Arabs.

• King Æthelred II of Northumbria sends military assistance to the Picts, in their fight against the invading Scots (approximate date).

• Máel Sechnaill mac Máele Ruanaid becomes the first High King of Ireland.

• A Saracen Arab expeditionary force from Africa, consisting of 11,000 men and 500 horses, raid the outskirts of Rome, sacking the basilicas of Old St. Peter's and St. Paul's Outside the Walls.

• April 22 – Emperor Wu Zong (Li Chan) dies after a 6-year reign. He is succeeded by his uncle Xuān Zong, as Chinese ruler of the Tang Dynasty.
• Jang Bogo, a powerful maritime hegemon of Silla, is assassinated by aristocratic elements at his garrison headquarters by Yŏm Chang (or 841).

• Danish Vikings 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).
• Viking Age: The Vikings plunder the Lower Rhine, as part of their attacks on the Empire of Francia.
• The Saracens, under the Berber leader Kalfun, capture the Byzantine city of Bari (Southern Italy). He becomes the first ruler of the Emirate of Bari, and expands his influence on the Italian mainland with raids.^[25]

• August 10 – Caliph Al-Wathiq dies of dropsy after a five-year reign. He is succeeded by his brother al-Mutawakkil.

• November 24 – 847 Damascus earthquake

• January 24 – Pope Sergius II dies of gout after a 3-year reign. He is succeeded by Leo IV, as the 103rd pope of Rome.
• April 21– Rabanus Maurus, a Frankish Benedictine monk, becomes archbishop of Mainz after the death of Odgar.

• Summer – Bordeaux, capital of Aquitaine, falls into the hands of Viking raiders. King Charles the Bald sends a Frankish fleet to lift the siege. Despite destroying some Viking longships on the Dordogne River, they fail to save the city. The Abbey of Saint-Pierre in Brantôme is sacked.
• 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".
• Frankish forces under Count (comté) William of Septimania assume authority over the counties of Barcelona and Empúries (modern Spain).
• 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]

• The armies of Brycheiniog and Gwent clash in the battle of Ffinnant (Wales). King Ithel of Gwent is killed in the fighting (approximate date).
• Máel Sechnaill mac Maíl Ruanaid, High King of Mide, defeats a Norse Viking army at Sciath Nechtain in Ireland (approximate date).

• The Medieval Cholas in Southern India start to rule (approximate date).

• Pope Leo IV builds (on the opposite of the Tiber River) the Leonine City, a fortified three-kilometre wall that encircles the Vatican Hill and Borgo, to defend Rome.^[28]
• The Roman Catholic church of Santa María del Naranco, on the slope of Monte Naranco (Northern Spain), is completed.

• 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]
• Frankish forces under King Charles the Bald invade southern France, and conquer the territory of Toulouse. He appoints Fredelo as count (comté) of Toulouse, who founds the Rouergue dynasty. Aquitaine is submitted to the West Frankish Kingdom.

• The Armenian prince Bagrat II begins a rebellion against Caliph Al-Mutawakkil, of the Abbasid Caliphate.

• 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.
• King Pyinbya of Burma founds the city of Bagan, located in the Mandalay Region, and fortifies it with walls.