Cluny Abbey in the context of Urban II

Pope Urban II (Latin: Urbanus II; c. 1035 – 29 July 1099), otherwise known as Odo of Châtillon or Otho de Lagery, was the head of the Catholic Church and ruler of the Papal States from 12 March 1088 to his death. He is best known for convening the Council of Clermont, which ignited the series of Catholic military expeditions known as the Crusades.

Pope Urban was a native of France and a descendant of a noble family from the French commune of Châtillon-sur-Marne. Before his papacy, Urban was the grand prior of Cluny and bishop of Ostia. As pope, he dealt with Antipope Clement III, the infighting of various Christian nations, and the Turkish invasions into Anatolia. In 1095, he started preaching for the start of the First Crusade (1096–1099). He promised forgiveness and pardon for all of the past sins of those who would fight to reclaim the Holy Land from Muslims and free the Eastern churches. This pardon would also apply to those fighting the Muslims in Spain. While the First Crusade resulted in the occupation of Jerusalem and expulsion of the Fatimids, Pope Urban II died before he could receive the news.

The Cluniac Reforms (also called the Benedictine Reform) were a series of changes within medieval monasticism in the Western Church focused on restoring the traditional monastic life, encouraging art, and caring for the poor. The movement began within the Benedictine order at Cluny Abbey, founded in 910 by William I, Duke of Aquitaine (875–918). The reforms were largely carried out by Saint Odo (c. 878 – 942) and spread throughout France (Burgundy, Provence, Auvergne, Poitou), into England (the English Benedictine Reform), and through much of Italy, northern Portugal and Spain.

William I (22 March 875 – 6 July 918), called the Pious, was the Count of Auvergne from 886 and Duke of Aquitaine from 893, succeeding the Poitevin ruler Ebalus Manser. He made numerous monastic foundations, most important among them the foundation of Cluny Abbey on 11 September 910.

Cluny (French pronunciation: [klyni]) is a commune in the eastern French department of Saône-et-Loire, in the region of Bourgogne-Franche-Comté. It is 20 km (12 mi) northwest of Mâcon.

The town grew up around the Benedictine Abbey of Cluny, founded by Duke William I of Aquitaine in 910. The height of Cluniac influence was from the second half of the 10th century through the early 12th. The abbey was sacked by the Huguenots in 1562, and many of its valuable manuscripts were destroyed or removed.

Anacletus II (died January 25, 1138), born Pietro Pierleoni, was an antipope who ruled in opposition to Pope Innocent II from 1130 until his death in 1138. After the death of Pope Honorius II, the college of cardinals was divided over his successor. Unusually, the election was entrusted to eight cardinals, who elected Gregorio Papareschi as Innocent II. A larger body of cardinals then elected Pierleoni, which led to a major schism in the Roman Catholic Church. Anacletus had the support of most Romans, including the Frangipani family, and Innocent was forced to flee to France. North of the Alps, Innocent gained the crucial support of the major religious orders, in particular Bernard of Clairvaux's Cistercians, the abbot of Cluny Peter the Venerable; and Norbert of Xanten, the archbishop of Magdeburg who established the Premonstratensians and held a high rank in the court of Emperor Lothar III.

The lack of support from these key figures left Anacletus with few patrons outside of Rome. Anacletus, with little remaining support, lived for several years and died with the crisis unresolved. In 1139 the second Lateran Council ended the schism, although opinion remained divided.