He then returned to the Cardinal, whose new assignment in France was actually to preach a crusade against Frederick II, the Hohenstaufen Emperor, who was again at war with Pope Gregory IX. Early in 1239, the Pope had again excommunicated the Emperor. Each had demanded an Ecumenical Council to settle their differences. The Pope was willing, but he planned that the council would meet under his auspices and in his territory. He would also bring to Rome all of the enemies of Frederick Hohenstaufen. It was at this point in 1240 that Teobaldo also became a Canon of the Cathedral of Lyons, at the request of the Canons made to Cardinal Giacomo de Pecorari when a vacancy in their number occurred. Pope Gregory's ecumenical council never took place, and he died on 22 August 1241.