Boniface IV Frederick (died July 1055) was the only son of

Boniface III of Tuscany Boniface III (also ''Boniface IV'' or ''Boniface of Canossa'') (c. 985 – 6 May 1052), son of Tedald of Canossa and the father of Matilda of Tuscany, was the most powerful north Italian prince of his age. By inheritance he was count (or lord) of ...

and Beatrice of Bar. He was young when his father died on 6 May 1052 and he inherited the great north Italian margraviate. His mother served as his

regent In a monarchy, a regent () is a person appointed to govern a state because the actual monarch is a minor, absent, incapacitated or unable to discharge their powers and duties, or the throne is vacant and a new monarch has not yet been dete ...

until 1054, when she married Godfrey, former

duke of Lower Lorraine The kings and dukes of Lorraine have held different posts under different governments over different regions, since its creation as the kingdom of Lotharingia by the Treaty of Prüm, in 855. The first rulers of the newly established region were k ...

. Godfrey was a traitor to

Henry III, Holy Roman Emperor Henry III (, 28 October 1016 – 5 October 1056), called the Black () or the Pious, was Holy Roman Emperor from 1046 until his death in 1056. A member of the Salian dynasty, he was the eldest son of Conrad II and Gisela of Swabia. Henry was rais ...

, and thus the marriage was considered traitorous. In 1055, Henry held a court at

Florence Florence ( ; ) is the capital city of the Italy, Italian region of Tuscany. It is also the most populated city in Tuscany, with 362,353 inhabitants, and 989,460 in Metropolitan City of Florence, its metropolitan province as of 2025. Florence ...

and arrested Beatrice, while Godfrey was rebelling in Lorraine. Henry bade Frederick come, but the child refused. It was no matter, for he died a few days thence and the margraviate passed to his sister Matilda.

Sources

Bonifaz II. Markgraf von Canossa-Tuszien (1052–1055).
{{s-end 1055 deaths Margraves of Tuscany House of Canossa Year of birth unknown Matilda of Tuscany