The character of the news from Constantinople continued constantly to be more and more distressing. The revenue was yearly decreasing. The money obtained in Europe was already spent, and the knights were driven to desperate expedients to obtain more. Copper was torn from the domes of the churches and other public buildings to be converted into coin. Empty houses were pulled down to supply fuel. The sacred relics, which in the eyes of the Crusaders constituted not only the most valuable treasures of the city but the talisman of its safety, were sold to meet pressing needs. The Sacred Crown of Thorns had been pledged for a sum of about seven thousand pounds, and when the time came for redeeming it, the Latins were not able to find the money. A Venetian endeavoured to obtain it in order to add to the prosperity of the Bride of the Seas, but Baldwin, possibly out of gratitude to Saint Louis of France, and with the object of obtaining a larger sum, preferred that it should be sent to France. After considerable difficulty and many negotiations, the sacred relic was redeemed and taken with solemn procession from Venice to Paris, where the king himself, clothed in penitential garments and barefoot, went out to meet it and to accompany it to its temporary resting-place. This was in 1239. Baldwin received from Louis, in recompense of his labour to obtain so valuable a prize, the sum of ten thousand marks. Nor was this the only relic which the crusading empire was obliged to convert into money. A large portion of the true cross, the lance, the sponge, and other objects, the parting with which must have cost Baldwin and his barons many a regret, were also sent to France in order to raise money.[16] [Sidenote: Prosperity of Nicene empire.] By July 1239 Baldwin had collected in the West all the money and forces available and started for Constantinople. The number of his army was greatly exaggerated by the rumours which preceded it and greatly alarmed the Greeks at Nicaea. He arrived at Constantinople at the end of December. John Vataces, in consequence of these rumours and as a precaution, allied himself with the Bulgarians. The armies of the two states attacked Constantinople. The Venetians saved the city by arriving in time to make it necessary to raise the siege. Then the Bulgarians made friends with the Latins and allowed a band of Comans (or Tur-comans) who had been driven over the Danube by the Mongols to pass through Bulgaria and take service with the Latins. The emperor of Nicaea could, however, play a similar game, and he induced a band of the same race, who formed excellent light cavalry, to settle on the banks of the Meander and in Phrygia.