814

Year 814 was a common year starting on Sunday of the Julian calendar, the 814th year of the Common Era and Anno Domini designations, the 814th year of the 1st millennium, the 14th year of the 9th century, and the 5th year of the 810s decade.

Events

April 13 - Byzantine–Bulgarian Wars: Over the winter Krum, ruler of the Bulgarian Empire, had assembled a huge army, for a campaign against the Byzantine Empire. But before he sets out for a major attack on Constantinople, he dies of a stroke. Krum is succeeded by his son Omurtag.
Europe
January 28 - Charlemagne dies of pleurisy in Aachen, after an almost 14-year reign as the first Roman Emperor of Frankish origin. He is embalmed and buried in Aachen Cathedral. Charlemagne is succeeded by his son Louis the Pious, as king of the Frankish Empire.
Louis I establishes himself at the imperial court of Aachen. He appoints Benedict of Aniane as his chief advisor on religious matters, and makes him abbot of Kornelimünster Abbey, which is founded by him.
Japan
Shinsen Shōjiroku, a record of the genealogy of the ancient Japanese noble families, is completed during the reign of Emperor Saga.
By topic

Byzantine Iconoclasm: Conflict erupts between Emperor Leo V and Patriarch Nikephoros, on the subject of iconoclasm. The latter is excommunicated.