The Union of Lyons was achieved on condition that the Emperor should recognize filioque, azyme (unleavened bread), and the supreme authority of the pope; to all these stipulations, in the name of Michael, George Acropolitas took oath. Michael also expressed to the pope his readiness to support by troops, money, and provisions the proposed joint crusade for the liberation of the Holy Land, but he stipulated that peace be established with Charles of Anjou so that the Emperor, in diverting all his forces to the East, need not fear attack from the West.
Neither side was pleased with the results of the union. As was to be expected, Michael met with stubborn resistance among the great majority of the Greek clergy. An antiunion council against Michael Palaeologus and John Beccus was held in Thessaly. Moreover, the idea of a crusade could not be agreeable to the Emperor, who was unable to forget the warning of the Fourth Crusade. There was the additional difficulty that Michael Palaeologus was on good terms with the sultan of Egypt, the sworn enemy of the Latins of Syria.
From 1274 to 1280, five papal embassies came to Constantinople in order to confirm the union. But in 1281 the new pope, the Frenchman Martin IV, whom Charles of Anjou set upon the papal throne, broke the union and gave entire support to Charles' aggressive plans against Byzantium. But Michael regarded himself as formally bound by the Union of Lyons to the day of his death.