In 865, a large force of Viking warriors invaded England. The Saxons, who were the ruling class at the time, were unable to mount an effective defense and were soon driven out of their kingdom. The Vikings then established their own kingdom, which they called Danelaw.
For centuries, the Vikings and the Saxons lived side by side in England, with the Vikings controlling the north and east of the country and the Saxons controlling the south and west. However, there was always tension between the two groups. In 1066, this tension boiled over into war. The Saxons, under King Harold Godwinson, faced off against the Vikings, under King Harald Hardrada, at the Battle of Stamford Bridge. Although Harold won this battle, he was defeated just a few days later at the Battle of Hastings by another Viking army, led by William the Conqueror. This victory gave William control of all of England.
So did the Vikings conquer England? In a sense, yes. They may not have held onto their conquest for long, but for a time they were able to establish their own kingdom in this country.