Osferth was the result of a union between Alfred and a serving girl named Eadgyth. He was an embarrassment to the deeply religious Alfred. He was enrolled as a novice monk. Nephew of Leofric
Uhtred saw Osferth and recognized him. After Osferth said he did not want to be in the Church, Uhtred took him into his service. When Father Beocca objected, Uhtred pointed out that Osferth would probably die the first time he fought in a shield wall, thereby relieving Alfred of his embarrassment, Beocca saw Uhtred's point. During the battle for London, Osferth jumped from a wall into the midst of the enemy and seriously wounded Sigefrid, a Danish warlord, crippling him. At Alfred's demand, Uhtred sent Osferth back to Wintancester with Pyrlig but Alfred soon allowed Osferth to return. After a second battle, Osferth killed Sigefrid and Uhtred gave him Sigefrid's sword.
Osferth developed into a competent warrior and led a portion of Uhtred's troops.