1236, and dispatched a mission led by the Dominican André de Longjumeau to acquire Holy relics, including the Crown of Thorns, parts of the True Cross, the Holy Lance, and the Holy Sponge. The Sainte Chapelle in Paris was begun by Louis whose chapel would hold and display his sacred objects in a large reliquary. (The reliquary and associated vessels were melted down during the French Revolution. The crown is currently in the Louvre, saved from the 2019 fire at Notre-Dame de Paris.) Papal blessing for the Crusade would come later. Innocent IV Innocent IV became pope on 25 June 1243, facing both religious and political crusades. At that time, the papacy was engaged in a feud with emperor Frederick II, then under excommunication. Frederick was at first pleased with his election, but it was soon clear that Innocent intended to carry on his predecessors' traditions. Fearing a plan to kidnap him, Innocent IV left Rome in March 1244, pursued by the emperor’s cavalry, travelling to Lyons. He wrote to Louis IX, asking for asylum, which was cautiously refused. In exile, the pope presided over First Council of Lyon in 1245. The council directed a new Crusade under the command of Louis IX, who had already taken the cross, with the objective of reconquering the Holy Land. With Rome under siege by Frederick, that year the pope also issued his Ad Apostolicae Dignitatis Apicem, formally renewing the sentence of excommunication on the emperor, and declared him deposed from the imperial throne and that of Naples. From Gregory IX, Innocent IV inherited a Prussian Crusade targeting the Orthodox Russians. Innocent was also the first to seriously face the challenge posed by the Mongol incursion into Europe in the course of 1241. After Lyons, Innocent sent envoys to the Mongols (see below) who also negotiated with Russian princes over church union with Rome. As both Daniel Romanovich of Galicia-Volhynia and Yaroslav II, grand prince of Vladimir, seemed to respond positively, the pope abandoned the idea of an alliance with the Mongols and aimed instead to form a grand alliance with the Russians to counter the Mongol threat. In January 1248, Innocent joined with Heinrich von Hohenlohe, Grand Master of the Teutonic Order, in warning Daniel and Yaroslav’s son Alexander Nevsky of impending Mongol attacks on Christianity and to unite under papal protection in the defense against the invaders. Both Russian princes accepted