Year 680 (DCLXXX) was a leap year starting on Sunday (link will display the full calendar) of the Julian calendar. The denomination 680 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years. Events By place Byzantine Empire Byzantine–Bulgarian War: The Bulgars under Asparukh subjugate the country of current-day Bulgaria, north of the Balkan Mountains. Emperor Constantine IV leads a combined land and sea operation against the invaders and besieges their fortified camp in Dobruja. Battle of Ongal: The Byzantine army (25,000 men) under Constantine IV is defeated by the Bulgars and their Slavic allies in the Danube Delta. Bulgar cavalry force the Byzantines into a rout, while Constantine (suffering from leg pain) travels to Nesebar to seek treatment. Europe King Wamba is deposed after an 8-year reign, and forced to retire to a monastery. He is succeeded by Erwig who becomes ruler of the Visigothic Kingdom. King Perctarit makes his son Cunipert co-ruler of the Lombard Kingdom. He signs a formal peace treaty with Constantine IV. Pippin of Herstal becomes Mayor of the Palace of Austrasia. The emporium (market town) of Dorestad is founded near the mouth of the Rhine, and soon becomes a major trading settlement in the North Sea region (approximate date). Britain King Cædwalla of Wessex becomes overly ambitious in a power-struggle with his rival, King Centwine, for Wessex overlordship. He is banished into the forests of Chiltern and Andred. Arabian Empire Yazid I, son of Muawiyah I, becomes the sixth caliph (second Umayyad caliph) but Kufans in Mesopotamia rebel and invite Hussein ibn Ali (grandson of Muhammad) to take the throne. October 10 – Battle of Karbala: Forces under Yazid I kill Hussein ibn Ali and his closest supporters. This event leads to the civil war known as the Second Fitna. Asia In Japan, Princess Uno Sarara is unwell, and Emperor Tenmu begins the erection of the Temple of Yakushi-ji (Nara Prefecture). He makes 100 people enter religion as priests, wishing her to recover her health. By topic Religion September 17 – Theodore of Tarsus, archbishop of Canterbury, convenes a synod at Hatfield that clears the English Church from any association with the heresy of monothelitism. November 7 – The Third Council of Constantinople (Sixth Ecumenical Council) opens in Constantinople to settle the theological controversies of monoenergism and monothelitism,