There can be little doubt that the Council of the Stoglav in Moscow(1551), proclaiming supremacy of the Russian Orthodoxy over all other forms of the Greek-rite faith, the invasion of Belarus of Ivan IV("The Terrible"), the subsequent capture and destruction of Polacak(1563-1579) by the Russians, the estabkishment in 1589 the Patriarchate of Moscow as the "Third Rome", and the breaking after 1558 of the embargo of arms for Muscovy by Protestant England and Holland, were four events so fraught with danger for the Grand Duchy, that it had virtually no choice other than seek a political union with the Kingdom of Poland at Lublin in 1569, and renewed ecclesiastical union with Rome at Biarescie in 1596.
One of many Greek-rite clerics concious of the danger was Michael Rahoza. In 1576 he was appointed Archimandrite of the Ascension monastery in Minsk, which had remained vacant for several decades. He was consecrated the Metropolitan of Kiev in 1588 by the visiting Patriarch Jeremija of Constantinople who, "being unable to meet the financial demands of the Turks, had come to the North to look for money"(Guepin). Two years previously, the Patriarch of Antioch, Joachim had returned to his Turkish overlords, "carrying off large sums of money" collected from pious Orthodox believers in Belarus and Ukraine, which in turn helped the Turks to finance their campaigns against the Grand Duchy. The Greek Catholic(Uniate) Archbishop of Polacak, Josaphat Kuncevicz, stressed the peril in his reply to Chancellor Leu Sapeha's famous letter reproaching him with his hostility to the Constantinopolitan faction, the non-Uniate Cossacks of Ukraine and their then covert supporters, the Turks: "Are we to allow the Patriarch, a Metropolitan, a bishop, nay, even a pasha who has taken the precaution of donning a monks habit and assuming the title of Exarch, to come to this land with janissaries, on the pretext of a pastoral visitation, in order to spy and hatch treasonable plots? Are not we to prevent because this would indispose the Cossacks?". Minsk was to play an important part in the struggle for the restoration of the Florentine Union, as the only means of ending both the pretensions of the Tsar and Patriarch of Moscow, and of Constantinople, to political and ecclesiastical supremacy over "all the Russias and all the countries of the North". A council of the clergy of the Greek church was held in Minsk in 1620 presided over by Metropolitan Rutski with a view to obtaining adherence of the passive majority to the Union. The session, according to Syrakomla, appears to have been stormy, as a result of the bold intervention of the conservative anti-Union monk, Todar Jarmolicz. However, as the French church historian Guepin observed, "The extinction of the Ruthenian schism had become a matter of State".
The political union with Poland in 1569, and the problems involved in selection a joint ruler for the Kingdom and the Grand Duchy, resulted in some curious situations, as where a reluctant French Prince, Henri de Valois, brought back from Paris as ephemeral sovereign in 1574, by a delegation including Chancellor Radzivil, began appending his signature and seal as Grand Duke to the decrees written in the old Belarusian language. The union also altered the status of Minsk, which became instead of a Grand Ducal Namiestnictva(Shire), a standard Vajavodstva (County) of the Reczypaspalitaja(Commonwealth) with Hauryla Harnastaj as its first Vajavod(High Constable), Mikola Talvasz as Castellan and Bazyl Tyszkevicz as Starasta(Lord Lieutenant). Minsk became not only the seat of its own County Court and Land Tribunal, but also after 1581 a session town, in which the High Court of the Grand Duchy would sit when on circuit, the privelege it shared with Vilnia and the former capital Navahrudak. An occational pleader in the Minsk Courts was Todar Jeulaszeuski, who in his diary mentions his appearances at the sessions there in 1583. During the wars against Ivan the Terrible(1563-1579) Minsk once again served as operational headquaters for the Grand Ducal armies, and the King and Grand Duke Zhyhimunt III(Pol. II) sojourned there during the campaigns of 1563 and 1568. His successor Zhyhimunt IV(Pol. III) confirmed the city in its priveleges, granted the merchants the right to hold two Fairs each year and endowed municipality with additional lands in 1592.Mialecii Smatrycki
This was not always appreciated by the local population, stirred up by false rumors of impeding liturgical and festival changes, and fearful of the interference of an increasingly Polish-oriented sovereign into the affairs of the Grand Duchy. Mialecii Smatrycki (1577 - 1633), for a time hostile to, but later a supporter of the Uniate cause, has been received at the Salamarecki estate at Siomkava, near Minsk, on his return from Leipzig, and was said by Syrakomla to have written a part of his anti-Uniate polemical work Threnos of the Complaint of the Eastern Church during his stay there. When the Union of Biaresce was signed in 1596, many of the inhabitants of Minsk accepted it without protest. Those who did not follow the advice of the Vilnia Holy Ghost Confraternity, obtained from the Minsk magistrates in 1613 the grant of land for a church by the Niamiha, and called for non-Uniate priests from Vilnia to service it. The Grand Duke, who resented the establishment of these non-Uniate confraternities, which, with their schools and fund-raising activities for Muslim-occupied Constantinople, began to look very much like a hostile state within a state, sent two Uniate Greek-rite priests with royal letter-patents to seize the church building. The fair minded city fathers, however, appear to have been sympathetic to the Minsk cofraternity, and received the royal envoys, Luckebicz and Hainski, with some coldness, declaring that the city council had many other worries apart from the church affairs, and in the event nothing was done. Indeed, the first decade of the 17th century had been a time of sharp famine and plague, as well as of outbreaks of fire in the city(1602), so their calm had some justification. The three attempts in August 1616 on the newly established non-Uniate Cathedral confraternity, led by a shoemaker Danila Palavinka, to seize the Holy Ghost Cathedral, followed by the unlawful detention by the mob of the Catholic and Uniate burgomasters Aliaksej Philipovicz and Siamion Chatkevicz merely served to strengthen the fears of the peaceful majority of the townspeople over the political undertones of the Confraternity's campaign, and to advance the cause of the Greek Catholics. The publication in 1617 by Liavon Kreuza's Oborona Jednosti Cerkovnoj ("Defense of the Union") in reply to Smatrycki's Threnos was a skillful and convincing polemical work, which won over many waverers of the Union.
The Cathedral of the Holy Ghost
Since 1596 the bitterest dispute had arisen between the two factions over the ownership of Church property. These resulted in two outbreaks of unrest in Minsk(1597, 1616), and the martyrdom of the Uniate Archbishop of Polacak Josaphat Kuncevicz(1580 - 1623); they were finally settled at the conciliation meeting between the contending parties, held in Minsk in 1625. Both the Uniate Metropolitan Jasep Veniamin Rucki and the non-Uniate Metropolitan Peter Mohila attended the conference, which took place at a time when Muscovite rulers, weaked by internal strife, driven back from Novgorod and Smalensk, and at odds with Cossacks, were not in a position to interfere with the affairs of the Grand Duchy. Another Uniate School of SS. Cosmo and Damian opened in 1619. At this time also were built the Dominican monastery(1622), the Bernadine convents(1628, 1642), and the Basilian Church of the Holy Ghost(1645), all in the Upper Town, as well as the Basilian convent of the Holy Trinity in the Trinity suburb(1630). A privelege was also granted by the Grand Duke Uladzislau I (Pol. IV) in 1633 to the Basilian convent of the Holy Ghost and the Orthodox Confraterity of SS. Peter and Paul to establish printing presses; in the same year the increasingle wealthy Confraternity established a hospital and a school "for the instruction of Christians and their children". By the mid-17th century the Uniate churches in Minsk had seven confraternities owning houses, shop and land; the majority of the city churches and their endowments however remained in the hands of Greek Catholics, secure from the Turkish Sultan and the Russian Tsar.
Thereafter Minsk enjoyed several decades of prosperity during which trade flourished. A number of merchant corporations were established after 1552 -- the Guild of Metalworkers(1591), the Jewellers(1592), the Merchant Tailors(1592), the Shoemakers(1609), the Saddlers(1622), the Barbers(1635), and the Skinners(1647). Other guilds included Hatters, Tile-makers, Cooks, Carpenters, and Furriers. Churches, town houses, and public places were embellished, and culture generally (iconography, music, sculpture, and the applied arts) reached high levels of achievement.