union agreement was signed and Isidore returned to Eastern Europe. Sylvester Syropoulos and other Greek writers charge Isidore with perjury because he accepted the union, despite his promise to Vasili II. Council of Ferrara It is possible that Isidore had been a pupil of the neoplatonist Gemistus Pletho, and went with his teacher and two of Pletho's other students, Bessarion and Mark Eugenikos, to attend the Council of Ferrara, which was intended to negotiate the reunion of the Orthodox and Catholic Churches. The large delegation of theologians and philosophers set out with a great following on 8 September 1437, travelled via Riga and Lübeck, and arrived at Ferrara on 15, August, 1438. On the way, he caused offense by his friendly conduct towards the Latins. At Ferrara and at Florence, where the council moved to in January, 1439, Isidore was one of the six chief speakers on the Byzantine side. Together with Bessarion he steadfastly worked for the union, and never swerved afterwards in his acceptance of it. After the council, Pope Eugene IV made him his legate for all Ruthenia and Lithuania. While returning to Moscow, news reached Isidore, at Benevento, that he had been made Cardinal-Priest of the Title of St Peter and Marcellinus. This was one of the few cases at the time in which a person not of the Latin Rite was made a cardinal. From Buda, in March 1440, he published an encyclical calling on all Rus' bishops to accept the union, but when he at last arrived in Moscow (Easter, 1441), and proclaimed the union in the Kremlin church, he found that Vasily II and most of the bishops and people would have none of it. Then, at Vasily's command, six Rus' bishops met in a synod, deposed Isidore, and imprisoned him. The Grand Duchy of Moscow princes denounced the union with Rome, but Isidore persisted. On his return from Italy, during his first Pontifical Divine Liturgy in the Dormition Cathedral in the Moscow Kremlin, Isidore had a Latin Rite crucifix carried in front of the procession and named Pope Eugene IV during the prayers of the liturgy. He also read aloud the decree of unification. Isidore passed a message to Vasili II from the Holy See, containing a request to assist the Metropolitan in spreading the Union in Rus'. Three days later, Isidore was arrested by the Grand Prince and imprisoned in the