Career
Christened Frederick, he was a younger brother of Godfrey III, Duke of Lower Lorraine, and part of the Ardennes-Verdun dynasty that would play a prominent role in the politics of the period, which included their strong ties to the abbey of Saint Vanne. Frederick would initially be archdeacon of a cathedral church in Liege called Saint Lambert and later became abbot of Monte Cassino. He was raised to the cardinalate by Pope Victor II and, for some time, discharged the function of papal legate at Constantinople.
He was with Leo IX in his expedition against the Normans and at one time had to take refuge from Emperor Henry II in Monte Cassino.
Five days after the death of Pope Victor II, he was chosen to succeed him as Pope Stephen IX.
