John VIII Palaiologos or Palaeologus ( Greek : Ίωάννης Η' Παλαιολόγος , IĹŤannÄ“s VIII Palaiologos , 18 December 1392 – 31 October 1448), was the penultimate reigning Byzantine Emperor , ruling from 1425 to 1448. Wikipedia Repeatedly the court had discussed the question of making their cause a universal one by reuniting their church with the Roman Catholic. Preliminary negotiations had already taken place. Greek ambassadors had appeared at (he Council of Constance. Emperor Manuel had shown a certain zeal in the cause of union, but chiefly from political motives. Now John VIII. (Figs. 88 and 89) returned to the matter with the honest purpose of bringing it to a satisfactory conclusion. The emperor himself and a large retinue of clerics and theologians sailed to Venice, in 1438. Thence they went to Ferrara, where the anti-council of Eugenius IV. was sitting. But here no conclusion was reached. In Florence, however, whither the pope transferred the council on acc...