997

By place

Byzantine Empire

• July 16 - Battle of Spercheios: Byzantine forces, under General Nikephoros Ouranos, defeat the Bulgarians at the Spercheios River in Greece. During a night battle, the Bulgarian co-ruler Samuel is wounded; he and his son Gavril Radomir evade capture, by feigning death among the bodies of their slain soldiers. Samuel sets off to Bulgaria, and retreats with the remnants of his army, into the Pindus Mountains. Ouranos returns to Constantinople, with 1,000 heads of Bulgarian soldiers and 12,000 captives.

  Europe

• Al-Mansur, the de facto ruler of Al-Andalus, assaults and partially destroys the city of Santiago de Compostella. He is accompanied in his raid by Christian Portuguese lords, who all receive a share of the booty. On their way, they sack the cities of Zamora and León.
• Summer - Roman of Bulgaria dies in captivity in Constantinople. He is succeeded by his brother Samuel who takes the Bulgarian title of tsar. He possibly receives his 'imperial crown' from Gregory V.
• King Stephen Držislav of Croatia dies after a 28-year reign. His three sons, Svetoslav, Krešimir III and Gojslav, open a violent contest for the throne, weakening the kingdom and allowing Samuel to encroach on the Croatian possessions along the Adriatic.
• Winter - Emperor Otto III travels to Italy, leaving the government of the Holy Roman Empire in the hands of his aunt, Matilda of Quedlinburg. He is accompanied by Bishop Gilbert of Aurillac, his teacher and advisor.
• Trondheim is founded by King Olav Tryggvason. This will function as the main city and capital of Norway, until Bergen is founded in 1070.

  England

• King Constantine III dies after a 2-year reign. Possibly murdered by a dynastic conflict between two rival lines of royalty. He is succeeded by Kenneth III as sole ruler of Alba.

  Central Asia

• Sabuktigin, founder of the Ghaznavid Dynasty, dies after a 20-year reign. He is succeeded by his son Ismail as emir of Ghazna. But many in the court favor his elder brother Mahmud.

  China

• May 8 - Emperor Tai Zong dies at Kaifeng after 21-year reign. He is succeeded by his son Zhen Zong as the third ruler of the Song Dynasty.

  By topic

Religion

• Spring - Pope Gregory V is exiled during a rebellion led by Crescentius II, patrician of Rome. The Crescentii family appoints Giovanni Filagato as an antipope under the name John XVI, until 998.
• April 23 - Adalbert, exiled bishop of Prague, organises a mission to convert the Old Prussians in north-east Poland. On his way, Adalbert is murdered by pagans on the Baltic coast. His body is bought back for its weight in gold by Duke Bolesław I.
• The first documented reference of Gdańsk is made by Adalbert. During his mission he baptises the inhabitants of the city called Gyddannyzc.