Excerpts from Books and Wikipedia
"In 885 Guthrum, the leader of the Danes, broke the agreement he had made with Alfred after the Battle of Edington, and invaded Kent with a large force. Alfred responded by capturing London, forcing the Danes to abandon their base in the south." Other advancements made by Alfred were permanent garrisons called burhs or boroughs from which many market towns originated. He also built a number of ships to prevent coastal raids. [Furtado: 1001 Days]