Battle of Stamford Bridge

On September 25, 1066, at the Battle of Stamford Bridge, the English army under King Harold II defeated the invading Norwegian army led by King Harald Hardrada and Harold's brother Tostig. Both were killed in battle. From the article:

"The Battle of Stamford Bridge in Yorkshire, England on 25 September 1066 CE saw an army led by English king Harold II (r. Jan-Oct 1066 CE) defeat an invading force led by Harald Hardrada, king of Norway (r. 1046-1066 CE). Hardrada, aided by Harold's renegade brother Tostig, had managed to inflict a defeat on two English earls at the Battle of Fulford Gate a few days before, on 20 September, but Harold's army marched north to gain total vengeance, and both Hardrada and Tostig were killed at Stamford Bridge. Harold may have been victorious but his decision to promptly march south and face another invading army, this one led by William, Duke of Normandy (reigned from 1035 CE), would lead to catastrophe. At Hastings, on 14 October 1066 CE, Harold was killed and his army defeated, allowing the Normans to take over England."