Who is John of Ingleheim from Pope Joan and what is their importance?

Joan of Ingleheim is daughter of the Canon of Ingleheim and his wife, Gudrun, a Saxon heathen he rescues when he is a missionary. Joan is their youngest child, and outlives her two older brothers, as well as her parents. Being an extremely bright and resourceful person, Joan manages to save herself from a Viking attack by disguising herself as a man. Giving up her feminine identity, Joan finds it easier to attain the learning she craves and becomes involved in the world.