The 870s was a decade that began on 1 January 870 and ended on 31 December 879.
|Centuries:||8th century – 9th century – 10th century|
|Decades:||840s 850s 860s – 870s – 880s 890s 900s|
|Years:||870 871 872 873 874 875 876 877 878 879|
|Categories:||Births – Deaths – Architecture|
Establishments – Disestablishments
- The Danes invade England (870) and conquer East Anglia. Several battles are fought with Wessex, but then peace is made (871). The Danes start the Danelaw in other parts of England. In 876, the Danes attack Wessex again, and in 878 king Alfred the Great of Wessex has to retreat to a single fort in the marshes of Somerset, but later that year he defeats the Danes, and England is divided in a Danish part in the northeast and a Wessex part in the south and west.
- In the southwest of England, the Cornish continue to be driven back, with their King Dungarth (or Doniert or Dumgarth) drowning in battle around the middle of the decade.
- 872 — Battle of Hafrsfjord. Harald Fairhair unites Norway.