By the mid-9th century, much of England had fallen to the 'Great Heathen Army.' However, in 878, King Alfred the Great of Wessex defeated the Viking leader Guthrum at the Battle of Edington. This victory led to the Treaty of Wedmore and the establishment of the Danelaw—a region of northern and eastern England where Viking laws and customs prevailed. This division of England significantly influenced the development of the English language, as Old Norse words (like 'sky,' 'window,' and 'law') integrated into Old English. The Danelaw era transformed the Vikings from mere raiders into settlers, farmers, and traders, eventually leading to a blended Anglo-Scandinavian culture.