When King Edward ascended the English throne in 1042 A.D, he was in a weak position. His dynasty, the House of Wessex, had been out of power for the previous 26 years, superseded by Canute and his sons. He himself came to the English throne having spent most of his life in Normandy among Normans and Norman clergymen; it is more than likely he spoke Norman French more readily that Anglo-Saxon.
Additionally, Edward commanded no inherent base of power in England; he was heavily reliant on the earls of England, Godwin Earl of Wessex among them. It was Godwin that had brought Edward's name forward as King; it was Godwin who supplied his daughter Edith as Edward's wife. But Godwin - and all of the earls -were also jealous of their own administrative authority within their fiefdoms; a powerful king did nothing to advance that agenda.
As Edward moved into power, he began to outlaw and dismiss men put in place by Canute and his sons and recruited Normans into his retinue as well as into some higher clergy; this was not surprising as to Edward, these men would have represented trustworthy men to the king - and an alternate power base.
In 1046 A.D. Earl Godwin's eldest son, Swein, was outlawed for kidnapping an Abbess and keeping her for a year. Swein ended up in Denmark, but returned in 1048 A.D. only to be driven off again. Earl Godwine continued to pressure the King for the return of his son, even after Swein had killed his own cousin (1048 A.D.). The continued pressure of Godwin for his son's return, compounded by the appearance of control by Godwin and his sons of a fleet to protect England from German raiders and the fact that Edward's marriage with Edith was proving to be barren, provoked Edward into action. In 1051 A.D. Godwin and his sons were outlawed, their lands taken from them, and his wife Edith was to be divorced.
Godwin and his sons fled: Godwin to Bruges, France, Harold and his brothers to Dublin in Viking Ireland. Both father and sons began recruiting a mercenary army. They re-invaded in 1051 A.D., first as small piracy raids, then sailing up the Thames through London. Edward's lack of support was revealed and he was forced to negotiate. Godwin was restored to power and he and his family to his lands and Edith was restored to her position as queen; some of the more odious Norman bishops fled, eventually back to Normandy, taking with them Godwin's which had been offered as hostages for their good behavior. All was as it had been before the outlawing, with one exception: the inability of Edward to enforce his will and the power of Godwin and his sons was apparent.
Godwin did not long outlive this victory and died in 1052 A.D, as his did his eldest son (and bone of contention) Swein. Harold Godwinson ascended to the title of Earl of Essex - at Edward's decision; Edward and Harald did not have the contentious relationship of Edward and Godwin. The service of Harold and his family during this time, as far the records show, were what was to be expected between sovereign and earl.
In the mid-1050's, with the issue of the childless marriage at hand, Edward came up with what was perhaps a novel idea for an heir, A member of the royal house - an athling - remained alive: Edward the son of Edmund Ironsides. He had been exiled when Hardecanute had become king and had - at least to England - been lost to knowledge. It now appeared that he as located in the Kingdom of Hungary. In 1056, a retinue - seemingly including Harold Godwinson - was sent to Hungary to retrieve the future king. It was a task that would have required great diplomatic skill as the party had to make its way across the Channel to the Holy Roman Empire, then to Hungary, then back to England. This, the party accomplished - all to have Edward die in 1057 A.D. shortly after his arrival.
By 1062 A.D. the power of the Godwinsons' was at its height; they controlled five of the six earldoms of England. Harold led an invasion of Wales in 1062 which successfully ended in the head of Gruffydd King of all Wales being delivered to Harold, who sent it on to King Edward. Harold demonstrated tactical ingenuity, using a fleet to invade Wales and then drive the Welsh into the mountains, denying them the countryside (a strategy to be used successful by Edward I in his conquest of Wales).
In 1064 A.D, for reasons which now remain unclear, Earl Harold sailed to Normandy. It is unclear why he sailed to Normandy; history is largely silent and Norman sources (given following events) are highly unreliable. It is possible the trip was simply a rescue mission to plead for his brother and cousin; it is possible he was just "blown off course". No matter what happened, he was captured and transferred to William, Duke of Normandy. The Duke feted Harald; they undertook a campaign together in Brittany. Upon their return, William revealed that he wished for Harald to support his claim as King of England upon the death of Edward the Confessor.
Where could William, a man only distantly related to Edward, get such an idea? Historians guess that one of the fleeing bishops in 1051, Robert of Jumieges, came to the King with a story of Edward's wish to make him his heir. Whether this was real or just a story spread by a bitter man who had to flee the country, William chose this opportunity to use it to his advantage.
Harold, faced with the choice of imprisonment and possible death, swore the oath in a cathedral on holy relics, an oath that was considered binding in Medieval European and Catholic eyes. Possibly he was offered to retain his position as Earl of Wessex and marry William's daughter; he was given gifts and his nephew Hakon and released to England, burdened with an oath.
Harold returned to England, now clearly understanding that William of Normandy intended to claim the throne of England.
The last two years of Edward's reign became complicated. Northumbria in 1065 A.D. rose in revolt against Tosti, Earl of Northumbria and Harald's brother, due to a tax increase. The rebels rose up, ravaging their way South until they were met by Earl Harold. A civil war seemed possible, King Edward and Queen Edith and Earl Tosti against the thegns and men of Northumbria. Harold came down in his negotiations on the side of the rebels and against his brother; Tosti fled to Flanders and the old laws under King Canute were restored.
But time was running out for King Edward. His health began to fail in late 1065 and it appeared likely that he did not have much longer. Edward Athling's son Edgar was alive, but too young to become king. As the Christmas court came into being, the King, the Queen, the bishops and archbishops, and the great nobles of the realm were present. If Edgar was too young to be king and William was undesirable, only two other potential claimants remained. One was with them in court and there is no doubt that Harald Godwinson lobbied all heavily on his own behalf.
On 05 January 1066 A.D., Edward the Confessor died. As he lay dying, he transferred the kingship to Harald Godwinson.
(Author's note: I would not have been able to provide near the detail about Earl Godwin, Earl Harold, and the Godwin sons without Ian Walker's book Harold: The Last Anglo-Saxon King. It focuses on this period and these people in a way other works I consulted did not.)
Brooke, Christopher: From Alfred to Henry III 871-1272. Norton Library: USA, 1961.
Hollister, C. Warren: The Making of England 55 B.C. to 1399. D.C. Heath and Company: United States, 1976.
Trevelyan, G.M.: History of England Volume 1: From the Earliest Times to the Reformation. Anchor Books: USA, 1953