In the 11th century the Great Schism took place between Rome and Constantinople, which led to separation of the Church of the West, the Roman Catholic Church, and the Eastern Orthodox Church. There were doctrinal issues like the filioque clause and the authority of the Pope involved in the split, but these were exacerbated by cultural and linguistic differences between Latins and Greeks. Prior to that, the Eastern and Western halves of the Church had frequently been in conflict, particularly during periods of iconoclasm and the Photian schism.
The East-West Schism, or Great Schism, separated the Church into Western (Latin) and Eastern (Greek) branches, i.e., Western Catholicism and Eastern Orthodoxy. It was the first major division since certain groups in the East rejected the decrees of the Council of Chalcedon (see Oriental Orthodoxy), and was far more significant. Though normally dated to 1054, the East-West Schism was actually the result of an extended period of estrangement between Latin and Greek Christendom over the nature of papal primacy and certain doctrinal matters like the filioque, but intensified by cultural and linguistic differences.
The "official" schism in 1054 was the excommunication of Patriarch Michael Cerularius of Constantinople, followed by his excommunication of papal legates. Attempts at reconciliation were made in 1274 (by the Second Council of Lyon) and in 1439 (by the Council of Basel), but in each case the eastern hierarchs who consented to the unions were repudiated by the Orthodox as a whole, though reconciliation was achieved between the West and what are now called the "Eastern Rite Catholic Churches." More recently, in 1965 the mutual excommunications were rescinded by the Pope and the Patriarch of Constantinople, though schism remains.
Both groups are descended from the Early Church, both acknowledge the apostolic succession of each other's bishops, and the validity of each other's sacraments. Though both acknowledge the primacy of the Bishop of Rome, Eastern Orthodoxy understands this as a primacy of honour with limited or no ecclesiastical authority in other dioceses.
The Orthodox East perceived the Papacy as taking on monarch type characteristics that were not in line with the church's tradition.
The final breach is often considered to have arisen after the capture and sacking of Constantinople by the Fourth Crusade in 1204. Crusades against Christians in the East by Roman Catholic crusaders was not exclusive to the Mediterranean though (see also the Northern Crusades and the Battle of the Ice). The sacking of Constantinople and the Church of Holy Wisdom and establishment of the Latin Empire as a seeming attempt to supplant the Orthodox Byzantine Empire in 1204 is viewed with some rancour to the present day. Many in the East saw the actions of the West as a prime determining factor in the weakening of Byzantium. This led to the Empire's eventual conquest and fall to Islam. In 2004, Pope John Paul II extended a formal apology for the sacking of Constantinople in 1204; the apology was formally accepted by Patriarch Bartholomew of Constantinople. Many things that were stolen during this time: holy relics, riches, and many other items, are still held in various Western European cities, particularly Venice.