Pope Stephen IX (, christened Frederick; c. 1020 – 29 March 1058) was the head of the Catholic Church and ruler of the Papal States from 3 August 1057 to his death in 29 March 1058. He was a member of the Ardenne-Verdun family, who ruled the Duchy of Lorraine, and started his ecclesiastical career as a canon in Liège. He was invited to Rome by Pope Leo IX, who made him chancellor in 1051 and one of three legates to Constantinople in 1054. The failure of their negotiations with Patriarch Michael I Cerularius of Constantinople and Archbishop Leo of Ohrid led to the permanent East-West Schism. He continued as chancellor to the next pope, Victor II, and was elected abbot of the Benedictine monastery of Montecassino. Stephen was elected to succeed Victor on 2 August 1057. As pope, Stephen retained the Montecassino abbacy, enforced the Gregorian Reform, and continued Leo IX's efforts to expel Normans from southern Italy. He died in Florence, apparently poisoned by Romans, while endeavouring to crown his brother Godfrey the Bearded as Holy Roman emperor. Family Christened Frederick, he was a younger brother of Duke Godfrey the Bearded of Lorraine, and part of the Ardennes-Verdun dynasty that played a prominent role in the politics of the period. Another older brother, Duke Gothelo II of Lower Lorraine, died in 1046. His younger sister, Regelinde, married Count Albert II of Namur. Another sister, Oda, married Count Lambert II of Louvain. Frederick's youngest sister, Mathilda, was married to Count Palatine Henry I of Lotharingia. The family had strong ties to the abbey of St. Vanne. Pre-papal career Frederick held a canonry in St. Lambert's Cathedral in Liège and then became the archdeacon. In 1049, or perhaps 1051, he met Pope Leo IX, and was invited to Rome. He was appointed cardinal-deacon of Santa Maria in Domnica by Leo IX. He was also appointed "bibliothecarius et cancellarius", in succession to Odo, the primicerius of Toul, who was named a bishop, and whose latest signature as chancellor is on 16 January 1051. Frederick appears as a signatory to papal documents from 9 March 1051 to 21 December 1053. Travels As chancellor, Frederick's duties in preparing and issuing papal documents, especially bulls, required his constant attendance on the pope. He therefore followed Leo in various travels. He participated in the pope's southern journey from May to August 1052; he signed a