Halfdene

Halfdan Ragnarsson
"Halfdene", Halfdan's name as it appears in the Peterborough Chronicle at least 200 years later.
King of Northumbria
Reign	876–877
Predecessor	Ricsige
Successor	Guthfrith
King of Dublin (Disputed)
Reign	875–877
Predecessor	Eystein Olafsson
Successor	Bárid
Died	877 Strangford Lough
Father	possibly Ragnar Lodbrok, or historical basis for a legendary character
Mother	possibly Aslaug, or historical basis for a legendary character

Halfdan Ragnarsson (Old Norse: Hálfdan; Old English: Halfdene or Healfdene; Old Irish: Albann; died 877) was a Viking leader and a commander of the Great Heathen Army which invaded the Anglo-Saxon kingdoms of England, starting in 865. According to the tradition recorded in the Norse sagas he was one of the sons of Ragnar Lodbrok, and his brothers included Björn Ironside, Ivar the Boneless, Sigurd Snake-in-the-Eye and Ubba. He was the first Viking King of Northumbria and also claimed the Kingdom of Dublin. He died at the Battle of Strangford Lough in 877 trying to press his Irish claim.

Halfdan was one of the leaders of the Great Heathen Army which invaded the Anglo-Saxon kingdom of East Anglia in 865. According to the Norse sagas this invasion was organised by the sons of Ragnar Lodbrok, of whom Halfdan was one, to wreak revenge against Ælla of Northumbria. Ælla had supposedly had Ragnar executed in 865 by throwing him in a snake pit, but the historicity of this explanation is unknown. The invaders are usually identified as Danes, although the tenth-century churchman Asser stated that the invaders came "de Danubia", which translates as "from the Danube", the fact that the Danube is located in what was known in Latin as Dacia suggests that Asser actually intended Dania, a Latin term for Denmark.