There were many attempts to force Orthodox Christians in Poland to join the church union and become subject to the rule of the Popes. The first attempt took place in the mid-13th century. Daniel, the duke of Volhynia and Halicz was encouraged to join the union by the emissary of Pope Innocent IV, an Italian Franciscan Joannes de Piano Carpine. Having gathered the bishops, ighumens and boyars, the duke refused subjecting the Orthodox Church of Halicz to the pope. This did not discourage the Pope from further efforts to draw the Ruthenian dukes into the union. All the union missions in 1247 and 1248 were unsuccessful. Another attempt at forcing the Orthodox Church into the union took place during the reign of Ladislaus Yahyello. The second attempt at introducing the Florence Union in Poland came in 1474, when the bishop of Smolensk, Mizael Pstrutsky became Metropolitan of Kiev. The problem of church union returned in the times of Alexander the Yahyellonian. In 1494 the prince married the daughter of the Moscow Tsar Ivan III Sophia Paleolog, a niece of the last emperor of Byzantium, who lived in Rome since the fall of Constantinople. At the same time, with the agreement of Alexander the Yahyellonian, Joseph Bulharynowich, became the Metropolitan, He was accepted as Metropolitan by the Patriarch Nifont in 1500. After receiving the Patriarch's blessing the Metropolitan addressed the Pope expressing his will to join the union of Florence. The preparation and the course of the synod in Brest, which led to bringing some of the Orthodox inhabitants of the Commonwealth of Poland and Lithuania was widely discussed in literature. Prior to this Hipatsy Potsiey and Cyril Terletsky went to Rome as plenipotentiaries of the king and episcopate. Upon coming to Rome in November 1595 the Ruthenian bishops presented 32 articles prepared by the synod as a kind of condition of accepting the union. They demanded Rome to accept their own separate tradition and identity. After the Ruthenian lords visited Rome the Pope sent letters to the king and Latin episcopate asking them to help the Ruthenian bishops organize a union synod. Meeting the assignations of the union project Sigismund III Vasa summoned, in a proclamation of 14 June 1596, the clergy and the faithful of the Orthodox Church to call a synod, during which unity between the Greek and Roman churches would be officially declared. New union projects concerning the Orthodox Church in Poland came into being after the reactivation of the Orthodox hierarchy by the Patriarch of Jerusalem in 1620-1621. Suggestions for a new synod were put forward in the parliamentary sessions in 1623, 1629 and 1636. In response to the Pope's call in 1644 an anonymous union memorial was created. It was sent to the Roman Curia. Peter Mohyla and Adam Kisiel are said to be the authors of this memorial. The authors of the memorial strongly criticized the Union of Brest and presented their own concept of joining the Orthodoxy with the Roman Church. According to Mohyla there are no essential differences between the Greek and Latin Church as far as faith is concerned. The only difference lies in the organizational structure and the rite traditions. Both churches were treated as equal and apostolic. In its essence the Union of Brest could not serve as a model for unity. It lacked 'pure and holy intentions '. The ostensible unity destroyed the identity of the Eastern Church. Mohyla's and Kisiel's project rejected the model of the Union of Brest, which led to severing the ties with the Orthodox community and Constantinopolitan patriarchate. The basic assumption of the Union memorial was agreement of the clergy and the faithful with Rome without severing the ties with Tsarogrod. This was not the last union attempt aimed at the Orthodox Church in Poland in the 17th century. However, the suggested union projects were only part of the plan of the state authorities and Rome to take over all Orthodox bishoprics and total eradication of the Orthodox church. The Vatican's interest in the Orthodox Church in Middle-Eastern Europe was renewed at the end of the First World War. Along with the new Eastern policy of the Vatican Polish bishops prepared plans for missionary activity among Orthodox believers. The new Byzantine-Slavic rite amounted to leaving the full rituality of the Eastern Church, while accepting the Pope as head of Church, adding the filioque to the faith symbol and introducing a few Roman Catholic holidays to the liturgic calendar. The synodal Russian rite was adjusted to Catholic dogmatics. Old Slavonic Orthodox language remained the language of liturgy, while the sermons were given in national languages - Russian, Ukrainian, Byelorussian and Polish. The looks of churches and liturgical clothes remained unchanged. The results of the new union action were unimpressive when compared to the span of the action and resources used to conduct it. According to the data of the Ministry of Religious Denominations and Public Enlightenment in 1927 there were 28 neo-Uniat parishes, 30 clergymen and 17000 faithful. The problem of the new union and conflicts connected with it ended with the beginning of the Second World War. After the Second World War very few Uniat parishes remained under the vjurisdiction of Latin bishops. It was only after 1989 that the Uniats separated from the Latin Church structure in Poland. Two Greek-Catholic dioceses of the Ukrainian rite were created by the Pope and given a wide autonomy within the Roman Catholic Church. With the 400th anniversary of the Union Council the subject of the Union of Brest and its consequences for the Christian community returned in academic literature. The problem of church union had a negative influence on the relations between the Catholic and Orthodox Churches in Poland.