EuropeApril 17 – Canute IV succeeds as king of Denmark on the death of his brother Harald III.
May 14 – William Walcher, Bishop of Durham, is killed by rebel Northumbrians. To punish the rebels, King William I of England sends his half-brother Odo of Bayeux to pacify Northumbria.
July 5 – Ísleifur Gissurarson, the first bishop in Iceland, dies while giving mass in Skálholt church.
Autumn – King William I of England's son Robert Curthose is sent to invade Scotland; he reaches as far as Falkirk.
October 14 – Battle on the Elster between the armies of the two rival brothers-in-law kings of the German states, Henry IV, King of the Romans and Rudolf of Rheinfelden meeting at the White Elster river in the Great Saxon Revolt civil war of the Holy Roman Empire. Rudolf is the victor but dies the following day at Merseburg of wounds received.
King William I of England, in a letter, refuses to accept Pope Gregory VII as his overlord.
King Alfonso VI of León and Castile establishes Latin liturgy in the Catholic Church in place of the Mozarabic Rite.
Osmund (bishop of Salisbury), builds Devizes Castle in England.
c. 1080–1100 – The Master of Daphni creates the mosaic of Christ Pantocrator in the central dome of the katholikon at Daphni Monastery in Greece.
AsiaThe Rubenid Principality of Cilicia gains independence after its founder, Ruben I, Prince of Armenia, succeeds in establishing his authority in the mountainous regions of Cilicia (approximate date).
The Seljuq-led Turkish tribes begin the Great Turkish Invasion of the Kingdom of Georgia.
The Song dynasty Chinese polymath scientist and statesman Shen Kuo begins his defensive military campaign against the Tangut people of the Western Xia Kingdom, successfully defending the invasion route to Yan'an.
AfricaThe Almoravid emir, Yusuf ibn Tashfin, conquers Tangier, Badis and Hunayn.
April 1 – Byzantine emperor Nikephoros III Botaneiates is overthrown by Alexios I Komnenos who is crowned on April 5, ending the Middle Byzantine period and beginning the Comnenan dynasty.
May 8 – Alfonso VI of Castile marries Constance of Burgundy.
October 18 – Byzantine–Norman wars: Battle of Dyrrhachium: Alexios I helps defend Albania from the Normans (the first recorded mention of Albania) but is defeated by Robert Guiscard, Norman Duke of Apulia and Calabria, outside the city of Dyrrhachium (Durrës), the Byzantine capital of Illyria. The Normans govern Albania from southern Italy until around 1100.
Corfu is taken from the Byzantine Empire by Robert Guiscard.
Turkish emir Tzachas conquers İzmir and founds a short-lived principality, emerging as the first sea power in Turkish history.
Battle of Mynydd Carn near St Davids in Wales: Gruffudd ap Cynan in alliance with Rhys ap Tewdwr (prince of Deheubarth) defeats the forces of Trahaearn ap Caradog, Caradog ap Gruffydd and Meilir ap Rhiwallon (who are all killed), allowing Gruffudd to claim the Kingdom of Gwynedd.
Construction begins on St. Canute's Cathedral in Odense, Denmark.
Pope Gregory VII writes a letter to the Bishop of Metz about Henry IV's behavior.
Construction of the Rochester Cathedral is completed in England.
The German Henry IV, Holy Roman Emperor besieges Rome and gains entry; a synod is agreed upon by the Romans to rule on the dispute between Henry and Pope Gregory VII.
Ottokar II succeeds his brother Adalbero (died 1086 or 1087) as margrave of Styria.
The Korean printing of the entire Buddhist Tripitaka is completed.
A military campaign advised by Shen Kuo fails.
The first mention of the German town of Hofgeismar is recorded.
EuropeSancho I of Aragon conquers Graus.
Alfonso VI of Castile conquers Talavera de la Reina.
Duklja conquers Bosnia.
In June, Henry IV, Holy Roman Emperor besieges Pope Gregory VII in Castel Sant'Angelo.
AfricaCeuta falls to the Almoravids after a five years siege.
Saint Bruno founds the Carthusian Order of monks.
Kyanzittha begins his reign in Burma.
Henry IV, Holy Roman Emperor is crowned Emperor by Antipope Clement III.
Rome is besieged by the Holy Roman Emperor Henry IV, and is then sacked by the Normans of Robert Guiscard, who intended to restore papal authority over the city.
Pope Gregory VII, who had been imprisoned by Henry IV at the Castel Sant'Angelo, Rome, is freed by Robert Guiscard.
During the struggle for power in Sweden, King Halsten is killed and his brother Inge the Elder is deposed in Svealand, only ruling Götaland for the next three years. The Svears take Blot-Sweyn as their king.
Antioch is captured by the Seljuk Turks from the Byzantines.
Chancellor Sima Guang and a group of scholars of the Chinese Song dynasty complete the compilation of the Zizhi Tongjian, an enormous written universal history of China in 294 volumes of 3 million written Chinese characters.
April 2 – Emperor Zhezong becomes emperor of Song Dynasty. Empress Dowager Gao cancels all the reform packages and dismisses pro-reform Wang Anshi.
May 25 – Alfonso VI of Castile enters the Islamic city of Toledo, Spain, and invites French knights to settle the central plateau of Spain.
The Domesday survey is commissioned by William I of England, apparently prompted by the abortive invasion of Canute IV of Denmark, to ensure proper taxation and levies.
Henry IV extends the "Peace of God" over his entire empire.
Katedralskolan in Lund, the oldest school in Scandinavia, is founded.
Vratislav, Duke of Bohemia, is crowned King.
By this year, the annual output of copper currency for the Chinese Song Dynasty reaches 6 billion coins a year, prompting the Chinese government to adopt the world's first paper-printed money later in the 1120s.
AsiaEmperor Shirakawa of Japan starts his cloistered rule.
The Imam Ali Mosque in Najaf is rebuilt by the Seljuk Malik Shah I after being destroyed by fire.
EuropeOctober 23 – Battle of Sagrajas: Alfonso VI of León and Castile is defeated by the Almoravids, who had been called into Spain by Abbad III of Sevilla.
The Domesday Book is completed in England.
Syracuse, the last Muslim stronghold in Sicily, is conquered by the Normans.
ReligionMay 24 – Pope Victor III succeeds Pope Gregory VII as the 158th pope, though he does not accept election until May 9, 1087.
AfricaMahdia campaign: The navies of Genoa and Pisa take the capital of the Zirids and occupy it for a year. Subsequently both republics obtain trading privileges.
AsiaEmperor Horikawa ascends to the throne of Japan.
End of the formal reign of Emperor Shirakawa, but not of his cloistered rule
EuropeMay 9 – The remains of Saint Nicholas are brought to Bari, Italy by local sailors.
September 9 – William II becomes King of England.
Inge the Elder returns to Svealand, kills Blot-Sweyn and anew proclaims himself King of Sweden.
A fire in London, England destroys much of the city including St Paul's Cathedral.
The Sharq al-Andalus falls under the domination of El Cid supported by the malik of Tortosa.
ReligionMay 9 – Pope Victor III formally accepts elevation as the 158th pope.
AfricaMansur ibn Nasir succeeds Nasir ibn Alnas as ruler of the Hammadid Dynasty.
EuropeA rebellion in England against William II of England is led by Odo of Bayeux.
The 6.5 Ms Tmogvi earthquake affects the Kingdom of Georgia, causing severe damage and many deaths.
Almoravid campaign in al-Andalus. Yusuf ibn Tashfin besieges Aledo but is forced to retreat by the arrival on the scene of the troops of King Alfonso of Leon and Castile.
The troops of the count of Barcelona reconquer the ancient archiepiscopal see of Tarragona (lost again in 1108). Berenguer de Lluçanés becomes the city's new archbishop
Arts and cultureThe Dream Pool Essays is published in this year by the polymath Chinese scientist and statesman Shen Kuo. His book represents the earliest known writing about the magnetic compass, movable type printing, experimentation with the camera obscura only decades after Ibn al-Haytham, and includes many different fields of study in essay and encyclopedic form, including geology, astronomy, botany, zoology, mineralogy, anatomy, pharmacology, geography, optics, economics, military strategy, philosophy, etc. Some of Shen's most advanced theories include geomorphology and gradual climate change, while he improves Chinese astronomy by fixing the position of the pole star and correcting the lunar error by plotting its orbital course every night for a continuum of five years. Shen's book is also the first to describe the drydock in China, and discusses the advantages of the relatively recent invention of the canal pound lock over the old flash lock.
The Chinese polymath statesman and scientist Su Song has the successful pilot model for his astronomical clock tower constructed in Kaifeng, China. It features an escapement mechanism and the world's oldest known endless power-transmitting chain drive to operate the armillary sphere, opening doors, and mechanical-driven mannequins that would rotate in shifts to announce the time on plaques.
EducationThe oldest extant university, the University of Bologna, is founded.
ReligionMarch 12 – Pope Urban II succeeds Pope Victor III as the 159th pope.
Work begins on the third and largest church at Cluny.
AsiaRama Varma Kulashekhara is crowned in Kerala.
Palmyra is destroyed by an earthquake.
EuropeNorthumbria in England is divided by the Normans into the counties of Northumberland, County Palatine of Durham, Yorkshire, Westmorland and Lancashire.
George II resigns the throne of Georgia in favor of his 16-year-old son, David IV.
August 11 – A powerful earthquake is recorded in Britain.
June 22 – Gaston IV of Bearn and the Frankish crusaders take the Aragonese city of Monzón from the emir of Zaragoza.
ReligionCîteaux Abbey, the first Cistercian monastery, is founded in southern France.
The Synod of Melfi under Pope Urban II issued decrees against simony and the clerical marriage. Supposedly, this council declared that the concubines and illegitimate wives of these clerics were subject to slavery.
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