Sworn Sword: The Bloody Aftermath of 1066 England's Fate Hangs in Balance by James Aitcheson seems rather a cumbersome title, until you search "Sworn Sword" and find 4 other novels by the same name, including one by George R.R. Martin - pretty stiff competition.
The year is 1069 and three years have passed since the Battle of Hasting. Harold Godwineson is dead and Duke William of Normandy is the conqueror of England. This does not mean there is peace in the realm, however, as the Province of Northrumbia revolts.
Among the 2,000 Normans who march north is a soldier named Tancred. He is a knight seeking riches. But, it is not to be. The English rebels slaughter the Normans at Durham. Trancred manages to survive, but his lord does not.
Tancred commences his quest for vengeance for his lord's death, while Prince Eadgar, the last Saxon, marches to seize the kingdom he believes belongs to him. Tancred uncovers a plot that could sabotage William the Conqueror's victory.
From the synopsis, this sounds like a novel packed with action.