The reasons are covered in this section.
Edward the Confessor became King of England in 1042. When he died on January 4th 1066 he did not have a son or daughter to become the new King or Queen of England. There were three claimants to the throne of England. They were: -
Harold was the eldest son of Godwine, the Earl of Wessex, a very important English nobleman. When Godwine died in 1053 Harold became the new Earl of Wessex. While Edward the Confessor concentrated on the affairs of the church, Harold was left to run the affairs of the country including fighting the Welsh. As Edward the Confessor had no children the problem of who should become the next King of England was a serious issue.
In 1057 Edward the Exile and his family were invited back to England as Edward was a potential heir to the English throne. Edward the Exile was the son of Edmund II who had been King of England until 1016. When Edmund II died and Canute became king, Edward went into exile to escape being killed. Shortly after Edward the Exile returned to England he was murdered. This may have been arranged by Harold, who wanted the English throne for himself. Edward the Exile had a young son called Edgar, known as Edgar the Aethling, who was then the heir to the English throne.
When Edward the Confessor died in 1066 Edgar the Aethling was too young to rule and it was agreed by the noblemen of England that Harold should become the next King of England. His reign was very short and in less than a year he would be killed at the Battle of Hastings.
Harald Hardrada (or Harold Hardraada) was the King of Norway. He also ruled areas of northern Scotland including the Orkney Islands. Harald's claim to the English throne was weak, believing that it was his right to take the throne as Canute and Harthacnut had done previously. Harald had support from the Scottish King, Malcolm III, and also from Tostig, the brother of Harold Earl of Wessex. Tostig was the Earl of Northumbria but had been forced into exile after the Northumbrians rose up against his harsh rule. Harald Hardrarda and Tostig invaded England in September 1066.
Both William the Conqueror and Edward the Confessor had a common ancestor, Richard, Count of Normandy. In 1051 Edward the Confessor had problems restraining the Godwine family including Harold and in the hope that the Normans would assist him Edward offered William the right to claim the English throne after his death. William had also been visited by Harold of Wessex in 1064 and at a mysterious meeting it is suspected that Harold agreed to William's claim. When William later learnt that Harold was planning to take the English throne he was outraged and began invasion plans. William's invasion plans were backed by Pope Alexander II.
|1053||Edward the Exile invited to England|
|Harold Godwinson invited the exiled Edward the Exile back to England in the hope that he could claim the English throne from Edward the Confessor.|
|1057||Edward (the Exile) dies|
|Edward the Exile died in mysterious circumstances. Edward was the rightful heir the throne of England and Harold, Earl of Wessex benefited from Edward's death.|
|1065||Mysterious meeting in Normandy|
|A mysterious meeting is reported to have taken place in Normandy between William the Conqueror and Harold in 1065. In the meeting it was claimed that Harold agreed that William should become King of England when Edward the Confessor died. From what is known of Harold it seems unlikely that he would agree to something like this. We know that he went against this agreement when assumed the role as King after Edward's death.|
|Oct||Morcar becomes Earl of Northumbria|
|A rebellion against Tostig, Earl of Northumbria leads to Tostig fleeing to Flanders and Morcar becoming the new Earl.|