809

By place

Byzantine Empire

• Spring - Serdica (809)|Siege of Serdica]: Krum, ruler of the Bulgarian Empire, captures the fortress of Serdica, after a long siege. According to Byzantine sources, he massacres the garrison, sacks the city, and razes the city walls, before returning with much loot to Bulgaria. In the following years, Serdica will serve as a base for the expansion of the Bulgars to the south of the Balkans.

Europe

• A Byzantine fleet lands in the Venetian Lagoon, and attacks a Frankish flotilla at Comacchio, but is defeated. Doge Obelerio degli Antenori marries a Frankish bride, Carola; she becomes the first dogaressa of Venice.
• Aznar Galíndez I succeeds Aureolus, as count of Aragon. He is installed by King Louis the Pious, and remains a Frankish vassal.
• A rebellion in Gharb al-Andalus is crushed by the Emirate of Córdoba.

Abbasid Caliphate

• March 24 - Caliph Harun al-Rashid dies at Tus, on an expedition to put down an uprising in Khorasan. He is succeeded by his son Muhammad ibn Harun al-Amin.

Asia

• Emperor Heizei becomes ill, and abdicates the throne in favor of his brother Saga, who is installed as the 52nd emperor of Japan.
• Emperor Govinda III defeats his rival Nagabhata II, and obtains the submission of the Pala Empire.

By topic

Religion

• Council of Aachen (809): Frankish bishops adopt the filioque addition in the Creed. Pope Leo III intervenes, and refuses to recognize it as valid.