The Battle of Brunanburh, fought in the autumn of 937 at an unknown location, saw the English king, Aethelstan (r. 924-939), defeat a coalition of invading armies led by Constantine II of Scotland (r. 900-943) and Olaf Guthfrithson of Dublin (r. 934-939).
This is a companion discussion topic for the original content at https://www.worldhistory.org/article/2657/battle-of-brunanburh/.