Four days were spent in bringing over from the Asiatic side the provisions. Dandolo proposed to transport all the soldiers with his fleet and assault the water wall of the city, where, presuming upon the defence of their ships, the Greeks had left the fortifications weakest. But the crusaders, accustomed only to land operations, were averse to this plan and marched around the end of the Golden Horn. The fleet met them opposite the palace of Blachern, which occupied the corner of the northwestern wall and thus faced both land and sea. Though the walls extended for seven miles, this spot was regarded as the strongest of all. A wide moat was backed by three enormous lines of masonry, to capture one of which was only to lodge beneath the terrible menace of the others. Immense towers were so close together that to pass between them would be to challenge burial beneath the missiles which could readily be dropped from almost above their heads. Here twice within the preceding half-century the Greeks had discomfited the Arab hosts. At this point the Turks, under Mohammed II., were, two hundred and fifty years later, to make their victorious assault. The Greeks within the city were assisted by armies without, which, under Theodore Lascaris, the hero of the day on the part of the besieged, assailed the camps of the crusaders.

July 17th witnessed the grand assault. Boniface and Baldwin were in command. The battering-rams delivered their blows until one tower fell. Platform-ladders were quickly reared; fifteen Flemings secured a footing on the outer wall, but were slain or captured by men of their own blood, the hired Waring guard. The Venetians’ attack was more successful; their ships were covered with rawhides to protect them from the Greek fire, which flashed like liquid lightning from the walls above and spread in sheets of flame over the water. Bridges had been arranged from the crosstrees, which, as the vessels were anchored close to the shore, reached to the top of the walls. Every huissier carried a mangonel, which returned the stones hurled by the besieged.

The battle being contested thus far with equal skill, Dandolo gave orders to land; he himself set the example. Old and blind, he was carried in the arms of his attendants, and, with the banner of St. Mark floating above him, placed upon the shore. His heroism inspired his men. While the fight raged above their heads, on the bridges that ran from the rigging to the walls, the host below erected their scaling-ladders and emerged upon the parapets. Soon the gonfalon of St. Mark floated from a captured tower. Twenty-five more of these strongholds were quickly taken. The Venetians poured down through the streets of the city. Setting fire to the buildings, their progress was led by a vanguard of flame.

In this terrible emergency the emperor was caught by a momentary impulse of valor, and, putting himself at the head of sixty battalions, sallied from the city to strike the crusaders. The multitude of his men, their splendid accoutrements, and their unanticipated appearance led the crusaders to leave their assault upon the ramparts and range for defence behind their palisades. A more serious consequence of this valiant counter-attack was that it forced Dandolo to leave what he had already conquered and hasten to the assistance of his allies. But the Greeks had exhausted their fury in its first outburst, and made no further onset, contenting themselves with showering arrows from safe distance. Theodore Lascaris, the son-in-law of the emperor, in vain asked the imperial permission to assail the crusaders’ intrenchments. Alexius III. was content with the martial glory of having paraded before his foe; his troops, carrying the eagles of ancient Rome, as if the more to emphasize their shame, retreated without having struck a blow with the naked sword.

The next morning (July 18, 1203) the city was filled with a deeper sense of disgrace as the people learned that the emperor himself had stolen away during the night, taking with him a bag of gold and jewels, leaving his empire to him who could hold it, and his wife amid the spoil. Alexius III. was a despicable character, as cowardly as he was cruel, crafty, but without will power to sustain his own designs when they exacted much energy. His natural weaknesses had been increased by the habits of a voluptuary and drunkard until he had become but a crowned imbecile.

Realizing the condition of affairs, the troops, led by Constantine, the minister of finance, raised the cry for the deposed Isaac. The courtiers ran to his prison in the vaults of the Blachern, broke off his chains, and led the old and blinded man out, as he, having become hopeless of relief, believed, to execution, but, to his grateful surprise, to be seated again upon his throne. The wife of Isaac was sought out in an obscure quarter of the city, where she was living, grateful for even life; while the wife of the fugitive Alexius III. was thrust into a dungeon.

The recall of their former emperor could scarcely have been prompted by affection or even respect for him personally. Isaac was without character. Buffoons despised him for allowing himself to be the chief court fool. His ambition was divided between his sensuality and his extravagance; he had twenty thousand eunuchs, and spent four million pounds sterling on the housekeeping of his palace. His piety seems to have been limited to a belief in the prediction of a flattering patriarch, who had once assured him of an indefinite conquest of the world, for which, however, he made no preparation other than invoking an alliance with Saladin, whose sword he would buy to hew down his Christian opponents.

The news of the change of emperors was not assuring to the leaders of the Latins. Notwithstanding the pretence of having come to right the wrongs of Isaac, their plans necessitated either their own occupancy of the empire or the placing of young Alexius as the creature of their will upon the throne. Alexius, not Isaac, had made the bargain to pay the Westerners for their expedition two hundred thousand marks of silver, to furnish the army and fleet with provision for a year, and to bring the Greek Church into subjection to Rome. Would Isaac assume the same obligations?

The Latins sent a deputation to the palace; they passed between the lines of the same hired soldiers that yesterday guarded Alexius III., equally loyal to whatever hand fed them. There, upon a throne of superlative splendor, the Latin deputies saw the resurrected relic of a former monarch, blind and emaciated. To have rendered the picture sensationally complete, old and blind Dandolo should have stood before Isaac.

Villehardouin, who was one of the deputies, demanded of Isaac the confirmation of the contract made by young Alexius. On learning its nature, Isaac expressed his amazement and the impossibility of meeting it. The deputies assured the old man that his son should never be permitted to enter the city unless his father assumed his pledges. The emperor replied, “Surely the bargain is a hard one, and I cannot see how to carry it out; but you have done so much for him and me that you deserve our whole empire.” With hand trembling with age and fright he set to the compact the golden seal.