After successful raids by Danish
Vikings, significant parts of North-Eastern England, formerly
Northumbria, were under their control. Danish attacks into central England had been resisted and effectively reduced by
Alfred the Great, to the point where his son,
King Edward of Wessex, could launch offensive attacks against the foreigners. Edward was allied with the Mercians under his sister
Æthelflæd, and their combined forces were formidable. The allies launched a five-week campaign against
Lindsey in 909, and successfully captured the relics of
Oswald of Northumbria.