Edmund I ruled the Kingdom of the English from 939 to 946. In his youth, alongside his brother, King Aethelstan (reign 924-939), he defeated a Celtic-Viking alliance at the Battle of Brunanburh (937). Yet when Aethelstan died in 939 and Edmund inherited the crown, the Vikings returned, seizing York. Edmund spent much of his reign at war with the rulers of Viking York, eventually recovering the town in 944 and re-establishing the House of Wessex's control over the north. He took a close interest in Celtic affairs beyond his borders, maintaining close relations with Welsh and Scottish rulers and successfully invading the Kingdom of Strathclyde in 945.
This is a companion discussion topic for the original content at https://www.worldhistory.org/Edmund_I/.