"Gregory X convoked the general council on 31 March 1272...outlined three themes: union with the Greeks, the crusade, and the reform of the church. Regarding the third theme, which was not only traditional in medieval councils but was also required by the actual state of ecclesiastical morals, the pope in March 1273 sought the opinion of all christian people and asked for their help. After long preparatory arrangements the council assembled at Lyons and opened on 7 May 1274...The Greeks arrived late, on 24 June 1274, since they had been shipwrecked...The council had 6 general sessions: on 7 May 1274, 18 May 1274, 4 or 7 June 1274, 6 July 1274, 16 July 1274, and 17 July 1274. (from Papal Encyclicals.net, accessed 23 January 2012
