King Harald III, also known as Harald Hardrada, was a Norse king who ruled over Norway from 1047 until his death in 1066. He is often remembered for his ambitious attempts to expand his kingdom and his claim to the English throne. Before becoming king, Harald served as a mercenary and fought in various battles across Europe. Harald's most notable military action was the invasion of England in 1066, where he faced King Harold II at the Battle of Stamford Bridge. Despite initial success, Harald Hardrada was ultimately defeated and killed in this battle, marking the end of the Viking Age in England.