1088

By place

Europe

• Almoravid forces, under Sultan Yusuf ibn Tashfin, besiege Aledo, but are forced to retreat, by the arrival of Spanish troops of King Alfonso VI of Castile.
• Catalonian troops, under Count Berenguer Ramon II, reconquer Tarragona. He will rule Catalonia with his 6-year-old nephew Ramon Berenguer III, until he comes of age.

  England

• Spring - A rebellion led by William the Conqueror's half-brothers Odo of Bayeux and Robert, begins against King William II with the aim to remove him from the throne. Odo's revolt in Kent and Sussex is supported by nobles across the country.
• The Worcestershire rebellion led by Robert de Lacy is dealt with quickly by Wulfstan, bishop of Worcester, who calls on those knights and local landowners still loyal to William II to defend Worcester. Many of the rebels are captured or killed.
• William II calls the representatives of the fyrd to a meeting in London. He promises the people better laws, and the removal of taxes if they support him against the rebels.
• William II lay siege to Pevensey Castle where Odo of Bayeux has taken shelter with Robert. Odo is forced to surrender, and agrees to go to Rochester to convince the rebels to accept William as the rightful king of England.
• Summer - William II lay siege to Rochester Castle and puts down the revolt. Odo of Bayeux and the rebels surrender. William takes Odo's lands and exiles him to Normandy.

  Africa

• Nasir ibn Alnas, ruler of the Hammadids, dies after a 26-year reign. He is succeeded by his son Al-Mansur ibn al-Nasir.

  By topic

Arts and Culture

• The Dream Pool Essays is published by the Chinese polymath 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 Hasan ibn al-Haytham, which includes many different fields of study in essay and encyclopedic form, including geology, astronomy, archaeology, mathematics, pharmacology, magnetism, geography, optics, hydraulics, economics, military strategy, philosophy, etc. Some of Shen's most advanced theories include geomorphology and climate variability, 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 recent invention of the canal pound lock, over the old flash lock.
• Su Song, Chinese polymath scientist and statesman, invents the pilot model for his astronomical clock tower constructed in Kaifeng. It features an escapement mechanism – and the world's oldest known 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 :wikt:plaque|plaques.

  Education

• The oldest extant university, the University of Bologna, is founded in Italy.

  Geology

• April 16 - The 6.5 Tmogvi earthquake affects the southern provinces of Georgia, which causes the destruction of the castle of Tmogvi and many deaths.

  Religion

• March 12 - Pope Urban II succeeds Victor III as the 159th pope of the Catholic Church in Rome.