Alfred the Great stopped a Viking conquest of the whole of England. He united the Anglo-Saxons against the Vikings and created a sense of national identity
Eastern parts of England under the Danelaw developed own distinct place names and traditions. For example Viking settlements end in suffix "by" meaning village. Such as Grimsby. Also Thursday "Thors day."
Over time the peace treaty negotiated by Alfred allowed Anglo-Saxons and Vikings to live peacefully side-by side. Intermarriage and trade gradually led to mixing of the two cultures
After uniting to defeat the Vikings the other kingdoms in England acknowledged Alfred as their "overlord." Under his rule Anglo-Saxons called themselves Angelclynn-the English
Aethelred then carries out a mass killing of Vikings in England known as the St Brice's Day Massacre- during which Forkbeard's sister is killed in 1002