The new emperor had already shown that he believed in the necessity for a thorough reform of the Church. He was unable, however, to obtain the consent of Pope Pius IV to the marriage of the clergy, and in 1568 the concession of communion in both kinds to the laity was withdrawn. On his part Maximilian granted religious liberty to the Lutheran nobles and knights in Austria, and refused to allow the publication of the decrees of the council of Trent. Amidst general expectations on the part of the Protestants he met his first summoned Diet of Augsburg in March 1566. He refused to accede to the demands of the Lutheran princes; on the other hand, although the increase of sectarianism was discussed, no decisive steps were taken to suppress it, and the only result of the meeting was a grant of assistance for the war with the Turks, which had just been renewed. Maximilian would gather a large army and march to fight the Ottomans, but neither the Habsburgs nor the Ottomans would achieve much of anything from this conflict. The Ottomans would besiege and conquer Szigetvár in 1566, but their sultan, Suleiman the Magnificent, would die of old age during the siege. With neither side winning a decisive engagement, Maximilian's ambassadors Antun Vrančić and Christoph Teuffenbach would meet with the Ottoman Grand Vizier Sokollu Mehmed Pasha in Adrianople to negotiate a truce in 1568. The terms of the Treaty of Adrianople required the Emperor to recognise Ottoman suzerainty over Transylvania, Wallachia, and Moldavia.