The king of the Bulgarians did not spare his allies any more than his enemies; he burnt and demolished all the cities that fell into his hands. He ruined the inhabitants, dragged them in his train like captives, and made them undergo, in addition to the calamities of war, all the outrages of a jealous and barbarous tyranny. The Greeks, who had solicited his assistance, were at last reduced to implore the aid of the Latins against the implacable fury of their allies. The Crusaders accepted with joy the alliance with the Greeks, whom they never ought to have repulsed, and re-entered into Adrianople. Didymatica, and most of the cities of Romania, shook off the intolerable yoke of the Bulgarians, and submitted to the Latins. The Greeks, whom Joannice had urged on to despair, showed some bravery, and became useful auxiliaries to the Latins; and the new empire might have hoped for a return of days of prosperity and glory, if so many calamities could possibly have been repaired by a few transient successes. But all the provinces were strewed with ruins, and the cities and countries were without inhabitants. The hordes of Mount Hemus, whether victorious or conquered, still continued their predatory habits. They easily recovered from their losses; the losses of the Franks became every day more irreparable. The leader of the Bulgarians sought out everywhere the foes of the new empire; and, being abandoned by the Greeks of Romania, he formed an alliance with Lascaris, the implacable enemy of the Latins.
The pope in vain exhorted the nations of France and Italy to take up arms for the assistance of the conquerors of Byzantium; he could not awaken their enthusiasm for a cause that presented to its defenders nothing but certain evils, and dangers without glory.
Amidst the perils that continued to multiply, the Crusaders remained perfectly ignorant of the fate of Baldwin; sometimes it was said that he had broken his bonds, and had been seen wandering in the forests of Servia;[155] sometimes that he had died of grief in prison; sometimes that he had been massacred in the midst of a banquet by the king of the Bulgarians; that his mutilated members had been cast out upon the rocks, and that his skull, enchased in gold, served as a cup for his barbarous conqueror. Several messengers, sent by Henry of Hainault, travelled through the cities of Bulgaria to learn the fate of Baldwin; but returned to Constantinople, without having been able to ascertain anything. A year after the battle of Adrianople, the pope, at the solicitation of the Crusaders, conjured Joannice to restore to the Latins of Byzantium the head of their new empire. The king of the Bulgarians contented himself with replying, that Baldwin had paid the tribute of nature, and that his deliverance was no longer in the power of mortals. This answer destroyed all hopes of again seeing the imprisoned monarch, and the Latins no longer entertained a doubt of the death of their emperor. Henry of Hainault received the deplorable heritage of his brother with tears and deep regret, and succeeded to the empire amidst general mourning and sorrow. To complete their misfortunes, the Latins had to weep for the loss of Dandolo, who finished his glorious career at Constantinople, and whose last looks must have perceived the rapid decline of an empire he had founded.[156] The greater part of the Crusaders had either perished in battle, or returned to the West. Boniface, in an expedition against the Bulgarians of Rhodope, received a mortal wound, and his head was carried in triumph to the fierce Joannice, who had already immolated a monarch to his ambition and vengeance. The succession of Boniface gave birth to serious disputes among the Crusaders; and the kingdom of Thessalonica, which had exhibited some splendour during its short existence, disappeared amidst the confusion and the storms of a civil and a foreign war. In the brother and successor of Baldwin were united the civil and military virtues; but he could scarcely hope to restore a power so shaken on all sides.