878Centuries: 8th century 9th century 10th century
- The Danes force king Alfred the Great of Wessex to retreat to a fort in Athelney, Somerset.
- Battle of Ethandun (Edington), King Alfred the Great of Wessex defeats the Danes of the Danelaw under Guthrum.
- Treaty of Wedmore- signed by Alfred the Great and Guthrum- divides England between the Anglo-Saxons and the Danes .
- After a siege, 2 centuries of Muslim rule start in Syracuse.
- End of the excommunication of the later pope Formosus.