Empress Matilda
She was called "empress" because as a child she was married to Henry V, Holy Roman Emperor. She was Queen of England for a short time in 1141. The feud between Matilda and Stephen ended when Matilda's son, Henry, was named by Stephen as his successor. This was at the Treaty of Wallingford in 1153. Stephen's own chosen successor, his son Eustace, died in 1153.