Editing 877 (section)

==== Britain ====
* Autumn &ndash; King [[Alfred the Great]] raises a large force, and marches on the Viking camp at the city of [[Exeter]]. His army [[besiege]]s the [[Great Heathen Army|Great Summer Army]], led by  [[Guthrum]], and forces the Vikings to surrender. They flee north to [[Gloucester]], and settle in the [[Five Boroughs of the Danelaw|Five Boroughs]] (modern [[East Midlands]]).
* [[Battle of Strangford Lough]]: King [[Halfdan Ragnarsson|Halfdan I]] leaves for [[Ireland]], in an attempt to claim the [[Kingdom of Dublin]] from his rival [[Bárid mac Ímair]]. He is killed in battle at [[Strangford Lough]], and a probable [[interregnum]] follows in [[York]].
* [[Ceolwulf II of Mercia|Ceolwulf II]] is installed as [[Puppet monarch|puppet king]] of [[Mercia]]. The west of the kingdom comes under Ceolwulf's rule, while in the east the Five Boroughs begin as fortified Danish [[burh]]s.<ref>Hill, Paul (2009). ''The Viking Wars of Alfred the Great'', p. 68. {{ISBN|978-1-59416-087-5}}.</ref>
* The Vikings invade [[Wales]] once more, and King [[Rhodri the Great|Rhodri ap Merfyn]] ("the Great") of [[Kingdom of Gwynedd|Gwynedd]], [[Kingdom of Powys|Powys]] and [[Seisyllwg]] is forced to flee to Ireland (approximate date).
* King [[Causantín mac Cináeda|Constantin I]] is killed fighting Viking raiders, at the "Black Cave" in [[Fife]].<ref>{{cite book |last1=Lamont-Brown |first1=Raymond |title=St. Andrews: City by the Northern Sea |date=2006 |publisher=Birlinn |isbn=978-1-84158-450-8 |page=9 |edition=Illustrated, annotated |url=https://books.google.com/books?id=25BnAAAAMAAJ|language=en}}</ref> He is succeeded by his brother [[Áed mac Cináeda]] as ruler of [[Alba]] ([[Kingdom of Scotland|Scotland]]).