Tostig, who had been earl since 1055, is said to have provoked his nobles to rise against him by his harsh administration of justice, raising of tax levels, frequent absences from his earldom, and murder of several political opponents.
Tostig was sent into exile in Flanders, from where, disgusted at what he saw as his brother's betrayal, he shortly afterward raided the English coast, finally dying in arms against him at the Battle of Stamford Bridge.
By the end of this period there was a balance of power between the three main noble families, Harold Godwinson controlling the south of England, Siward the north, and Leofric and his son Ælfgar the centre.
This move, together with the creation of new minor earldoms and substantial redrawing of borders at Ælfgar's expense, left him possessed of a smaller Mercia than his father had ruled, while all the rest of England was held, under the king, by the Godwinsons, and principally by the brothers Harold and Tostig.
[4] The Vita Ædwardi Regis, an anonymous Latin life of Edward the Confessor written at about the time of the Norman Conquest, includes a description of Tostig's appearance and character.
It calls him strong, brave, handsome and graceful, open-handed, especially with gifts to the Church, trustworthy, faithful to his wife, secretive, shrewd, not rash, capable of restraint, but generally vigorous and unwearying in pursuing his purposes, sometimes to the point of overzealousness in confronting evil.
Northumbria was a turbulent, feud-ridden, and lawless province far distant from his own native Wessex, and its nobles may have resented having a southerner placed over them,[9] though it is also possible that having no connection with any of the three main Northumbrian factions (based around the house of Bamburgh, the see of Durham, and the Yorkshire nobility) he benefited from being seen as neutral.
[14][15][16] Tostig nevertheless felt able to frequently absent himself from his earldom, sometimes attending the king's court, sometimes his personal estates in Wiltshire, on one occasion collaborating with his brother Harold in an invasion of Wales, and on another making a pilgrimage to Rome.
This may have been an attempt to bring the local tax-levels, historically very low, more into line with those in the rest of England; or, since one third of such tributes were retained by the earl rather than the king, it may have been intended to defray Tostig's own expenses, such as those incurred by his campaigning in Wales.
[20] He is also reported by the Anglo-Saxon Chronicle to have become unpopular because he "robbed God", a mysterious phrase whose precise meaning can only be guessed at since he was a conspicuously pious and generous son of the Church.
[42] Tostig, together with his family and household, accepted the hospitality of his brother-in-law, Baldwin V, Count of Flanders, who made him his deputy in Saint-Omer and gave him the use of that port's revenues and knights.
Thereafter he shared the Norwegian king's fortunes, dying with him at Stamford Bridge on 25 September,[8] in a battle which did much to deplete the forces of its victor, Tostig's brother Harold, and to divert his attention from the defence of the south coast against the threat from Normandy.
[43] For contemporary observers, in particular the Vita Ædwardi Regis and the C recension of the Anglo-Saxon Chronicle, the Northumbrian Revolt and the rift between Tostig and Harold set in motion the events which culminated in the Norman Conquest.
[46][47] Others, however, such as N. J. Higham and Tom Licence hold the contrary opinion that it was in Harold's interests to further the ambitions of the brothers Edwin and Morcar, whose sister Ealdgyth he at some unknown date married and whose alliance he thereby gained.