Bruno von Egisheim-Dagsburg was born in 1002 to Count Hugo, a cousin of the emperor, and his wife, Heilewide. He was educated by Berthold, Bishop of Toul, and, after his ordination, became a canon of St. Stephen's at Toul. Bruno was consecrated bishop in 1027 and administered the Diocese of Toul for twenty years. When the German Pope Damasus II died in 1048, Bishop Bruno was selected by the emperor, Henry III, to succeed him.
Bruno "agreed to go to Rome, and to accept the papacy if freely elected thereto by the Roman people. He wished, at least, to rescue the See of Peter from its servitude to the German emperors. When, in company with Hildebrand he reached Rome, and presented himself to its people clad in pilgrim's guise and barefooted, but still tall, and fair to look upon, they cried out with one voice that him and no other would they have as pope. Assuming the name of Leo, he was solemnly enthroned 12 February, 1049".
"In a whirlwind pontificate of five years he travelled to Germany, France and northern Italy. Wherever he went he held a series of great reforming synods, which attacked the evils of simony, lay investiture and clerical marriage. . . In one week, Leo had asserted papal authority as it had never been asserted before."
--Eamon Duffy, in Saints and Sinners: A History of the Popes, Yale University Press, 2006.
"Leo chose a body of capable and reform-minded advisers from outside the Roman Curia: Hildebrand, who was to become Pope St Gregory VII; Frederick of Liege, who was to become Pope Stephen IX; and Humbert of Moyenmoutier. He also took advice from reformers such as St Hugh of Cluny and St Peter Damian."
In addition to the many reforms, Leo IX also made terrible mistakes. "In May 1053 he personally led an army against the Normans in southern Italy in defence of the Church's territories there, but he was easily defeated at Civitella and held captive for some months."
"The Byzantine Church claimed jurisdiction over parts of southern Italy and Sicily, and the patriarch of Constantinople was outraged by Leo's holding a papal synod at Siponto in 1050, by his appointment of Humbert as archbishop of Sicily, and finally by Leo's military interference. The pope wanted help from the East against the Normans and so sent a delegation, unfortunately headed by Humbert, to Constantinople at the beginning of 1054 to try to bring about a reconciliation. Both parties proved too intransigent, however, and when Humbert publicly excommunicated the patriarch and his followers, the patriarch responded by issuing his own excommunication against Humbert and the pope. This was in July 1054 and is usually regarded as the start of the schism between East and West. Although Leo was dead by the time the break came, he must be held responsible for the ill-judged delegation."
--Butler's Lives of the Saints
In The Investiture Controversy: Church and Monarchy from the Ninth to the Twelfth Century,  Uta-Renate Blumenthal, University of Pennsylvania Press, 1991, describes the changes made by Leo IX that "set a pattern that was followed for many centuries. During Leo's five-and-one-half year pontificate, he spent no more than about half a year in Rome. One conspicuous result was that papyrus almost ceased to be used; another, that the old curial script, in exclusive use until the end of the tenth century, was now replaced by minuscule script. . . . The rota, a double circle surrounding a cross, replaced a simple cross".
Click here  to see an example of this.
Blumenthal also gives details of Leo's disastrous foray against the Normans, in which his tiny army was slaughtered. "It is said that the pope never ceased to mourn his troops, who were soon to be revered as saints. Leo himself died within a year, on 19 April 1054".
Click here  to seem some pictures of Pope St. Leo IX.