Penda of Mercia
Most of Ælfflæd's life was spent as a nun. When she was about a year old, her father, King Oswiu of Northumbria, in thanksgiving for his victory over Penda of Mercia at the Battle of the Winwæd, handed her over to abbess Hilda to be brought up at Hartlepool Abbey. When Hilda left to found Whitby Abbey in 657 or 658, she brought Ælfflæd with her.