May 1 – After 353 years of being exiled to Lugo due to the Muslim occupation of the city of Braga, the Diocese of Braga is restored by order of Ferdinand I of León under Archbishop Pedro of Braga thanks to the advancing Christian forces during the Reconquista.
June – Denmark signs a treaty with England; Sweyn II and his forces leave the country.[1]
August 26 – Battle of Manzikert: The Byzantine army (35,000 men) under Emperor Romanos IV meets the Seljuk Turk forces of Sultan Alp Arslan near the town of Manzikert. Although the armies are initially evenly matched, as the Byzantines advance, the Seljuk Turks withdraw before them, launching hit-and-run attacks on the Byzantine flanks. While attempting to withdraw, the Byzantine army falls apart, either through treachery or confusion; the battle ends in a decisive defeat for the Byzantine Empire. Romanos is captured (though released by Alp Arslan within a week) and much of the elite Varangian Guard is destroyed; this will prove catastrophic for the Byzantine Empire.
Edwin, earl of Mercia, rebels against William I, but is betrayed and killed. His castle and lands at Dudley (located in the West Midlands) are given to William's Norman subjects.
October 7 – Alfonso VI becomes king of León and Castile, following the assassination of Sancho II. He is bestowed with the title of "Emperor of Spain", and is forced by El Cid (Rodrigo Diaz de Vivar), the standard-bearer of Sancho, to take an oath denying any involvement in his brother's death.
December 15 – Sultan Alp Arslan ("Heroic Lion") dies after a 9-year reign, during his campaign in Transoxiana. He is succeeded by his 17-year-old son Malik-Shah I, who is declared new ruler of the Seljuk Empire. Qavurt, a brother of Alp Arslan, claims the Seljuk throne for himself and occupies the capital of Isfahan.
Shen Kuo, Chinese polymathic scientist and statesman, is appointed as the head official for the Bureau of Astronomy – where he begins his work with the colleague Wei Pu on accurately plotting the orbital paths of the stars, planets, and moon three times a night for a continuum of five years.
Fall – Shen Kuo is sent to supervise Wang Anshi's program of surveying the buildup of silt deposits in the Grand Canal, outside the capital city of Kaifeng. Using an original technique, Shen successfully dredges the canal and demonstrates the formidable value of the silt gathered as a fertilizer.
Spring – Emperor Michael VII Doukas sends a Byzantine army to deal with Seljuk raiding in Cappadocia, supported with a mixed force of Norman and French mercenary heavy cavalry under Roussel de Bailleul. Roussel re-conquers some territory in Galatia and declares it an independent Norman state. Michael, enraged, sends another army led by his uncle, Caesar John Doukas and the veteran General Nikephoros Botaneiates to deal with the rising of the Norman threat in Asia minor. But the Byzantines are defeated and John is captured. Roussel marches with a force (3,000 men) across Bithynia to the Bosporus and sacks Chrysopolis, near Constantinople.[9]
Wang Anshi, Chinese chief chancellor of the Song dynasty, creates a new bureau of the central government (called the Directorate of Weapons), which supervises the manufacture of military armaments and ensures quality control.
Emperor Shenzong of Song establishes a Marine Office and a Goods Control Bureau north-west of Shanghai, allowing for the loading and unloading of freight.
The future Emperor Alexios Komnenos captures the Norman rebel Roussel de Bailleul in Amaseia. Roussel had established a principality in eastern Anatolia in 1073 after rebelling against Emperor Michael VII Doukas, basing his power on his western mercenaries and local support in exchange for protection against invading Turkmen.[15]
Roger de Breteuil is brought before the Great Council. He is deprived of his lands and sentenced to perpetual imprisonment. Ralph de Gael and Waltheof are charged as co-conspirators.
Summer – Shen Kuo, Chinese polymath scientist and statesman, solves a border dispute with the Liao dynasty by dredging up old diplomatic records. He refutes Emperor Dao Zong's bluffs point for point during a meeting at Mt. Yongan (near modern-day Pingquan), reestablishing the rightful borders of the Song dynasty.
Vietnamese forces under General Lý Thường Kiệt defend Vietnam against a Chinese invasion.
The Liao dynasty version of the Buddhist Tripiṭaka is completed (approximate date).
April – The Dictatus papae (a compilation of 27 statements of powers) are included in the registry of Gregory VII, in which he asserts papal authority over earthly as well as spiritual rulers.
December 8 – Gregory VII writes a letter of reprimand to Henry IV. He accuses him of breaching his word and continued support of excommunicated councilors.
February 22 – Gregory VII pronounces a sentence of excommunication against Henry IV at Rome. He is excluded from the Catholic Church, and all the bishops named by Henry are excommunicated.
A church council in Poitiers deposes Bishop Sylvester of Rennes who had bought his office in 1076. This leads also to the flight of Robert of Arbrissel to Paris where he begins his studies.[26]
Omar Khayyam, Persian mathematician and astronomer, calculates a 33 year calendar consisting of 25 ordinary years that include 365 days, and 8 leap years that include 366 days, the most accurate calculation of his time. Khayyam, in his Treatise on Demonstrations of Problems in Algebra, produces a complete classification of cubic equations and their geometric solutions (approximate date).
^John Julius Norwich (1991). Byzantium: The Apogee – The Disaster, p. 357. ISBN0-39453779-3.
^Brian Todd Carey (2012). Road to Manzikert: Byzantine and Islamic Warfare (527–1071), p. 155. ISBN978-1-84884-215-1.
^Fletcher, R. A. (1987). "Reconquest and Crusade in Spain c. 1050-1150". Transactions of the Royal Historical Society. 5. 37: 31–47 [35]. JSTOR3679149.
^"Fires, Great", in The Insurance Cyclopeadia: Being an Historical Treasury of Events and Circumstances Connected with the Origin and Progress of Insurance, p. 25. Cornelius Walford, ed. (C. and E. Layton, 1876).
^Claude Cahen (1968). Pre-Ottoman Turkey: a general survey of the material and spiritual culture and history c. 1070–1330. Trans. J. Jones-Williams, pp. 73–74 (New York: Taplinger).