778

Year 778 was a common year starting on Thursday of the Julian calendar, the 778th year of the Common Era and Anno Domini designations, the 778th year of the 1st millennium, the 78th year of the 8th century, and the 9th year of the 770s decade. The denomination 778 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

Arab–Byzantine War: Emperor Leo IV ("the Khazar") repulses an Abbasid invasion in Anatolia. A Byzantine expeditionary force under Michael Lachanodrakon, military governor of the Thracesian Theme, defeats the Muslim-Arabs at the fortress city of Germanikeia in Cilicia. He plunders the region and takes many captives, mostly Jacobites, who are resettled in Thrace.

A Frankish army under King Charlemagne invades Al-Andalus, and conquers the cities of Pamplona and Barcelona. However, the Franks are halted at Zaragoza, in the thughur or frontier zone of the Emirate of Córdoba.
August 15 - Battle of Roncevaux Pass : Charlemagne is defeated by the Basques. Among those killed is Roland, governor of the Breton March, who will be immortalized in the 11th century epic The Song of Roland. This marks the beginning of medieval French literature.
Saxon Wars: Widukind and his close followers return to Saxony from Denmark. He probably makes alliances with the Danes and the northwestern Slav tribes. Saxon rebels destroy the fortress of Karlsburg and sack Deutz, but are unable to cross the Rhine. They are driven back by the garrison of Koblenz, but then ambush and defeat the Frankish pursuers. Counter-attacking Frankish forces pursue the Saxons up the Lahn Valley, and defeat them near Leisa.

Unrest in Northumbria leads to King Æthelred I ordering the execution of three of his dukes. This considerably weakens his position.

Saxon raiders destroy many churches deep in Frankish territory. The Benedictine monks of Fulda Abbey hurriedly carry the relics of Saint Boniface over the Rhön Mountains to safety.

In Japan, the Kiyomizu-dera Buddhist temple is founded in Kyoto. Its main hall is built in 1633 without a single nail.