Pope Stephen IX was Pope

Pope

The Pope is the Bishop of Rome, a position that makes him the leader of the worldwide Catholic Church . In the Catholic Church, the Pope is regarded as the successor of Saint Peter, the Apostle...

 from August 3, 1057 to March 1058.

His baptismal name was Frederick of Lorraine , and he was a younger brother of Godfrey III, Duke of Lower Lorraine

Godfrey III, Duke of Lower Lorraine

Godfrey III , called the Bearded, was the eldest son of Gothelo I, duke of Upper and Lower Lorraine. By inheritance, he was count of Verdun and he became margrave of Antwerp as a vassal of the duke of Lower Lorraine...

, who, as Marquis of Tuscany

Tuscany

Tuscany is a region in Italy. It has an area of about 23,000 square kilometres and a population of about 3.75 million inhabitants. The regional capital is Florence ....

 (by his marriage with Beatrice of Bar

Beatrice of Bar

Beatrice of Bar was the marchioness of Tuscany from 1053 to her death as the wife of Boniface III of Tuscany...

, widow of Boniface III of Tuscany

Boniface III of Tuscany

Boniface III , son of Tedald of Canossa and the father of Matilda of Canossa, was the most powerful north Italian prince of his age...

), played a prominent part in the politics of the period.

Frederick, who had been raised to the cardinalate by Pope Leo IX

Pope Leo IX

Pope Saint Leo IX , born Bruno of Eguisheim-Dagsburg, was Pope from February 12, 1049 to his death. He was a German aristocrat and as well as being Pope was a powerful secular ruler of central Italy. He is regarded as a saint by the Roman Catholic Church, with the feast day of April 19...

 (1049–54), discharged for some time the function of papal legate

Papal legate

A papal legate – from the Latin, authentic Roman title Legatus – is a personal representative of the pope to foreign nations, or to some part of the Catholic Church. He is empowered on matters of Catholic Faith and for the settlement of ecclesiastical matters....

 at Constantinople

Constantinople

Constantinople was the capital of the Roman, Eastern Roman, Byzantine, Latin, and Ottoman Empires. Throughout most of the Middle Ages, Constantinople was Europe's largest and wealthiest city.-Names:...

, and was with Leo IX in his expedition against the Normans

Normans

The Normans were the people who gave their name to Normandy, a region in northern France. They were descended from Norse Viking conquerors of the territory and the native population of Frankish and Gallo-Roman stock...

 and at one time had to take refuge from Emperor Henry II

Henry II, Holy Roman Emperor

Henry II , also referred to as Saint Henry, Obl.S.B., was the fifth and last Holy Roman Emperor of the Ottonian dynasty, from his coronation in Rome in 1014 until his death a decade later. He was crowned King of the Germans in 1002 and King of Italy in 1004...

 (1002–24) in Monte Cassino

Monte Cassino

Monte Cassino is a rocky hill about southeast of Rome, Italy, c. to the west of the town of Cassino and altitude. St. Benedict of Nursia established his first monastery, the source of the Benedictine Order, here around 529. It was the site of Battle of Monte Cassino in 1944...

. Five days after the death of Pope Victor II

Pope Victor II

Pope Victor II , born Gebhard, Count of Calw, Tollenstein, and Hirschberg, was Pope from 1055 to 1057. He was one of a series of German reform Popes.-Life:...

 (who had made him cardinal-priest and abbot of Monte Cassino) he was chosen to succeed him as Pope Stephen IX. He enforced the policies of the Gregorian Reform

Gregorian Reform

The Gregorian Reforms were a series of reforms initiated by Pope Gregory VII and the circle he formed in the papal curia, circa 1050–80, which dealt with the moral integrity and independence of the clergy...

 as to clerical celibacy

Celibacy

Celibacy is a personal commitment to avoiding sexual relations, in particular a vow from marriage. Typically celibacy involves avoiding all romantic relationships of any kind. An individual may choose celibacy for religious reasons, such as is the case for priests in some religions, for reasons of...

, was planning for the expulsion of the Normans from Italy and the elevation of his brother to the imperial throne, when he was seized by a severe illness, from which he only partially and temporarily recovered. Stephen IX died at Florence

Florence

Florence is the capital city of the Italian region of Tuscany and of the province of Florence. It is the most populous city in Tuscany, with approximately 370,000 inhabitants, expanding to over 1.5 million in the metropolitan area....

 March 29, 1058, and is considered by the current-day Roman Catholic Church to have been succeeded by Pope Nicholas II

Pope Nicholas II

Pope Nicholas II , born Gérard de Bourgogne, Pope from 1059 to July 1061, was at the time of his election the Bishop of Florence.-Antipope Benedict X:...

 (1059–61), though others consider his successor to be Pope Benedict X (1058–59), officially regarded as an antipope

Antipope

An antipope is a person who opposes a legitimately elected or sitting Pope and makes a significantly accepted competing claim to be the Pope, the Bishop of Rome and leader of the Roman Catholic Church. At times between the 3rd and mid-15th century, antipopes were typically those supported by a...

.