When did the East-West Schism occur, leading to the break of communion between what are now the Roman Catholic Church and Eastern Orthodox churches?

The East-West Schism, also called the Great Schism and the Schism of 1054, was the break of communion between what are now the Roman Catholic Church and Eastern Orthodox churches, which has lasted since the 11th century.

A succession of ecclesiastical differences and theological disputes between the Greek East and Latin West pre-dated the formal rupture that occurred in 1054. Prominent among these were the issues of the source of the Holy Spirit, whether leavened or unleavened bread should be used in the Eucharist, the Bishop of Rome's claim to universal jurisdiction, and the place of the See of Constantinople in relation to the Pentarchy.

Inspired by the spirit of Vatican II that adopted the Unitatis Redintegratio decree on ecumenism in 1964 as well as the change of heart toward Ecumenism on the part of the Moscow Patriarchate that had occurred in 1961, the Vatican and 14 universally recognised autocephalous Orthodox Churches established the Joint International Commission for Theological Dialogue Between the Catholic Church and the Orthodox Church that first met in Rhodes in 1980 and is an ongoing endeavour.