998

By place

Europe

• Spring - Otto III retakes Rome and restores power in the papal city. Crescentius II and his followers barricade themselves in Castel Sant'Angelo. Otto's former tutor John Philagathos, who tries to escape into Campania, is pursued by German troops and captured. He is horribly mutilated – his ears, nose and tongue cut off and his eyes are gouged out. Crescentius surrenders at his stronghold and is beheaded. Otto reinstates his cousin, Gregory V, as pope of the Catholic Church.
• Croatian–Bulgarian War: Emperor Samuel launches a military campaign against the Kingdom of Croatia to prevent an alliance between the Serbian principality and the Byzantines. He seizes Dyrrachium and advances along the Dalmatian coast. The Bulgarian army is forced to withdraw into Croatian hinterlands, after the Siege of Zadar.
• Fall - Otto III makes Rome the administrative capital of the Holy Roman Empire and begins the construction of his imperial palace on the Palatine Hill. He restores the ancient Roman Senate to its position of prominence and adopts the title of "Emperor of the Romans". To this Otto adds the apostolic devotion formula servus Jesu Christi.
• Winter - King Robert II is excommunicated by Gregory V. For reasons of consanguinity, his second marriage to Bertha of Burgundy is not accepted by the Catholic Church.

  Arabian Empire

• Battle of Ghazni: The Afghan prince Mahmud defeats his younger brother Ismail in battle. He places Ismail for the rest of his life in comfortable captivity – and expands the realm of his late father, Sebuktigin, into the Punjab in northwestern India.
• Summer - Revolt of Tyre: The city of Tyre is stormed by forces of the Fatimid Caliphate. A Byzantine squadron attempts to reinforce but is repulsed by the Fatimid navy. The defenders are massacred or taken captive to Egypt. The Byzantine captives are executed.
• July 19 - Battle of Apamea: Byzantine forces under governor Damian Dalassenos besiege the fortress city of Apamea for control over northern Syria. The Fatimids send a relief army from Damascus – and defeat the Byzantines, Dalassenos in killed by a Kurdish officer in battle.

  Japan

• Byōdō-in Temple is built during the Heian Period on orders of Fujiwara no Michinaga, who uses the Buddhist temple as a countryside retreat villa.

  By topic

Religion

• Winter - Otto III makes a pilgrimage through middle Italy from Gargano to Benevento. Stopping by Monte Cassino, where he meets the hermit monk Romuald.
• Bishop Wulfsige III establishes a Benedictine abbey at Sherborne.