How did Alfred the great defeat the Vikings?

Alfred the Great defeated the Vikings through a combination of military strategy, fortification, and diplomacy. After suffering initial defeats, he reorganized his army, built fortified towns (burhs), and adopted a more defensive strategy. The decisive victory at the Battle of Edington in 878 forced the Viking leader Guthrum to accept peace and convert to Christianity, leading to the Treaty of Wedmore, which established boundaries between the Anglo-Saxons and Viking territories. Alfred's leadership and reforms laid the foundation for a unified England.