Beatrice was the daughter of Frederick II of Upper Lorraine and Matilda of Swabia. After their father’s death when she was about 9 or so, she and her sister Sophie were raised at the Imperial Court by their mother’s sister Empress Gisela.* She married Boniface of Tuscany c.1037 as his second wife and went on to have three children with him: Beatrice, Frederick, and Matilda.
They were married for only five years before Boniface was assassinated, leaving Beatrice with three very small children. She remarried Godfrey of Lorraine to strengthen her position. Unfortunately for her, this marriage came with several troubles. First, since Godfrey was her fourth cousin, they were violating incest laws, which led many to question the validity of the marriage.** Second, Henry III considered Godfrey a traitor and their marriage a threat to his power and promptly arrested Beatrice for marrying him and summoned the young Frederick to court.
Beatrice and Matilda, who was with her, were imprisoned. Frederick died before he could decide whether or not to appear before the Emperor. Her daughter Beatrice died sometime between her father’s death and her brother’s.*** Matters only changed when Henry III died and Godfrey reconciled with him, allowing the family to return to Italy.
Beatrice ruled Tuscany alongside Godfrey for the next several years. When he died in 1069, his son Godfrey technically became Margrave of Tuscany and Duke of Lorraine, but in practice Godfrey stayed in Lorraine while Beatrice ruled Tuscany with Matilda at her side and was considered by some to rule in her own right. She and Godfrey both died in 1076, leaving Tuscany to Matilda.
*Wife of the Holy Roman Emperor Conrad II.
**The two of them were each required by the Pope to found a monastery and vow celibacy.
***Some claimed that both Frederick and the younger Beatrice had been murdered.
Beatrice of Lorraine - Epistolae
Lazzari, Tiziana. "Before Matilde: Beatrice of Lorena 'Dux et Marchio Tusciae'" - Academia.edu
Barber, Malcolm. The Two Cities: Medieval Europe 1050-1320. London: Routledge, 1993.