One of the earliest and most informative sources is the Old English poem "Battle of Brunanburh" in the Anglo-Saxon Chronicle (version A), which was written within two decades of the battle. The poem relates that Æthelstan and Edmund's army of West Saxons and Mercians fought at Brunanburh against the Vikings under Anlaf (i.e. Olaf Guthfrithson) and the Scots under Constantine. After a fierce battle lasting all day, five young kings, seven of Anlaf's earls, and countless others were killed in the greatest slaughter since the Anglo-Saxon invasions. Anlaf and a small band of men escaped by ship over Dingesmere to Dublin. Constantine's son was killed, and Constantine fled home.