After the death of king Edward in 1066. Harold Godwinson (English) and William of Normandy (French) and Harald Hardrada (Norwegian) all argued to be king for various reasons like being related to Edward or Being promised the throne.
Harold was crowned king which got William and Harald angry
King Harold defeats Harald Hradara in the battle of Stanford Bridge.
After William hears about this he sets out to battle Harold and claim his throne
William beats Harold's tired army and deprived army and became known as William the conqurer
William becomes king. The reason William won the battle is because he waited for Harold's army to become tired and then attacked so he had btter tactics and was more prepared