Danelaw and the English
The 'Anglo-Saxon Chronicle' of 793 gives us a vivid picture of Britain under attack from Viking invaders.
'Terrible portents appeared over Northumbria and miserably frightened the inhabitants: these were exceptional flashes of lightning, and fiery dragons were seen flying in the air. A great famine followed these signs; and a little after that, in the same year on 8 June, the harrying of the heathen miserably destroyed God's church in Lindisfarne by rapine and slaughter.'
This 'harrying of the heathen' refers to the first Viking attack on English soil. This was followed for two centuries by a series of regular incursions and wars that lead to the settlement of many Vikings in these islands. The English language (along with much else) would never be the same again.
In 878, King Alfred agreed a truce with Guthrum, the Viking king. It required Guthrum to be baptised and, essentially, the division of England into the Anglo-Saxon southern kingdom and the Danelaw. The Danelaw included counties north of an imaginary line running from London to Bedford and then up to Chester. This was disputed land throughout the tenth century.
'... the interaction between the Viking settlers and their English neighbours ... helped to create the melting pot of two languages.'
Towards the end of this period, after the second wave of Viking invaders arrived under Olaf Tryggvason, the amount of Viking settlement in any area varied considerably. This was, in fact, the original north-south divide, in many ways the precursor of the one surviving today.
As a result of all this activity, the impact of Old Norse on the Old English dialects being spoken by the native population was significant, and had far-reaching implications. It was the interaction between the Viking settlers and their English neighbours, their trading and farming activities and their eventual intermarriage and assimilation that helped to create the melting pot of two languages.
Their combination in the north and east Midlands dialects gradually filtered into the English spoken throughout the rest of the country. The east Midlands dialect, in particular, was later to emerge as a major contributor in the growth of modern English.