That was the policy required, in the thirteenth century more than ever, by the most urgent interests of entire Christendom.

She was at grips with two most formidable foes and perils.  Through the crusades she had, from the end of the eleventh century, become engaged in a deadly struggle against the Mussulmans in Asia; and in the height of this struggle, and from the heart of this same Asia, there spread, towards the middle of the thirteenth century, over Eastern Europe, in Russia, Poland, Hungary, Bohemia, and Germany, a barbarous and very nearly pagan people, the Mongol Tartars, sweeping onward like an inundation of blood, ravaging and threatening with complete destruction all the dominions which were penetrated by their hordes.  The name and description of these barbarians, the fame and dread of their devastations, ran rapidly through the whole of Christian Europe.  “What must we do in this sad plight?” asked Queen Blanche of the king, her son.  “We must, my mother,” answered Louis (with sorrowful voice, but not without divine inspiration, adds the chronicler), “we must be sustained by a heavenly consolation.  If these Tartars, as we call them, arrive here, either we will hurl them back to Tartarus, their home, whence they are come, or they shall send us up to Heaven.”  About the same period, another cause of disquietude and another feature of attraction came to be added to all those which turned the thoughts and impassioned piety of Louis towards the East.  The perils of the Latin empire of Constantinople, founded, as has been already mentioned, in 1204, under the headship of Baldwin, Count of Flanders, were becoming day by day more serious.  Greeks, Mussulmans, and Tartars were all pressing it equally hard.  In 1236, the emperor, Baldwin II., came to solicit in person the support of the princes of Western Europe, and especially of the young King of France, whose piety and chivalrous ardor were already celebrated everywhere.  Baldwin possessed a treasure, of great power over the imaginations and convictions of Christians, in the crown of thorns worn by Jesus Christ during His passion.  He had already put it in pawn at Venice for a considerable loan advanced to him by the Venetians; and he now offered it to Louis in return for effectual aid in men and money.  Louis accepted the proposal with transport.  He had been scared, a short time ago, at the chance of losing another precious relic deposited in the abbey of St. Denis, one of the nails which, it was said, had held Our Lord’s body upon the cross.  It had been mislaid one ceremonial day whilst it was being exhibited to the people; and, when he recovered it, “I would rather,” said Louis, “that the best city in my kingdom had been swallowed up in the earth.”  After having taken all the necessary precautions for avoiding any appearance of a shameful bargain, he obtained the crown of thorns, all expenses included, for eleven thousand livres of Paris, that is, they say, about twenty-six thousand dollars of our money.