Viking Settlements c. 9th century

The Vikings first began raiding the British Isles towards the end of the 8th century. By the 860s, plundering had escalated to conquest; an invading Danish army seized York in 865, then occupied much of Northumbria in 871. Alfred the Great managed to defeat the Danes, and the subsequent Treaty of Wedmore (886) established a division of England between ‘Dane Law’ and Alfred’s Wessex and its dependencies. The Norwegian-led colonization in the northern isles and Scotland was less systematic. The impetus first came from chieftains driven abroad by Harald Fairhair’s unification of Norway. The isles would be occupied for centuries, but mainland settlement was more tenuous. In Ireland, the Vikings established footholds along the coast, and occupied more substantial territory round Dublin, but fought amongst themselves (possibly rival Danes and Norwegians) and were often bested in battle by the warlike Irish, who drove them from Dublin in 902.