When King Edward the Confessor died in 1066, leaving no heirs, three rival claimants appeared to dispute the throne of England: Harold Earl of Wessex, Harald III of Norway, and William, whose great aunt Emma was Edward's mother, wife of Ethelred the Unready. William also claimed that Edward, while in exile in Normandy, had promised him the throne and that Harold had pledged loyalty to him when knighted by William a few years previously.
Edward's will named Harold as his successor, and the new king, anticipating the reactions of the unsuccessful claimants, raised an army and a fleet to defend the coastline, and found himself assailed by his own brother Tostig as well as the king of Norway.
Meanwhile Duke William, feeling that a consecrated banner sent him by the Pope in his support gave him the moral high ground, assembled a force of 600 ships and 7000 men at St Valéry sur Somme, and after some weeks delay due to bad weather, set forth with his army in his Viking longships to meet Harold, who having defeated both Harald and Tostig, had marched south to oppose William. The decisive battle of Hastings, in which Harold was defeated after a day-long struggle, established William and founded the lineage which dominated both sides of the Channel until the thirteenth century.