all copies of the Jewish Talmud be confiscated. Following a public disputation between Christians and Jewish theologians, this culminated in a mass burning of some 12,000 handwritten Talmudic manuscripts on 12 June 1242, in Paris. Gregory was a supporter of the mendicant orders which he saw as an excellent means for counteracting by voluntary poverty the love of luxury and splendour which was possessing many ecclesiastics. He was a friend of Saint Dominic as well as Clare of Assisi. On 17 January 1235, he approved the Order of Our Lady of Mercy for the redemption of captives. He appointed ten cardinals and canonized Saints Elisabeth of Hungary, Dominic, Anthony of Padua, and Francis of Assisi, of whom he had been a personal friend and early patron. He transformed a chapel to Our Lady in the church of Santa Maria del Popolo in Rome. Gregory IX endorsed the Northern Crusades and attempts to bring Orthodox Slavic peoples in Eastern Europe (particularly Pskov Republic and the Novgorod Republic) under the Papacy's fold. In 1232, Gregory IX asked the Livonian Brothers of the Sword to send troops to protect Finland, whose semi-pagan people were fighting against the Novgorod Republic in the Finnish-Novgorodian wars; however, there is no known information if any ever arrived to assist. Struggle with Frederick II At the coronation of Frederick II in Rome, 22 November 1220, the emperor made a vow to embark for the Holy Land in August 1221. Gregory IX began his pontificate by suspending the Holy Roman Emperor Frederick II, for dilatoriness in carrying out the promised Sixth Crusade. Frederick II appealed to the sovereigns of Europe complaining of his treatment. The suspension was followed by excommunication and threats of deposition, as deeper rifts appeared. Frederick II went to the Holy Land and in fact managed to take possession of Jerusalem. Gregory IX distrusted the emperor, since Rainald, the imperial Governor of Spoleto, had invaded the Pontifical States during the emperor's absence. In June 1229, Frederick II returned from the Holy Land, routed the papal army which Gregory IX had sent to invade Sicily, and made new overtures of peace to the pope. The war of 1228–1230 is known as the War of the Keys. Gregory IX and Frederick came to a truce, but when Frederick defeated the Lombard League in 1239, the possibility that he might dominate all of Italy, surrounding the Papal States, became