Boniface of Montferrat and Doge Dandolo gradually talked over the more scrupulous Baldwin and his friends, and the crusading fleet was launched against Constantinople, after a treaty had been signed which bound Alexius Angelus and his blind father, Isaac II., to pay the Crusaders 200,000 marks of silver, send ten thousand men to Palestine, and acknowledge the supremacy of the Pope over the Eastern Church. In these conditions lay the germs of much future trouble. The Crusading armament reached the Dardanelles without having to strike a blow. The slothful and luxurious emperor let things slide, and had not even a fleet ready to send against them in the Aegean. He shut himself up in Constantinople, and trusted to the strength of its walls to deliver him, as Heraclius and Leo III. and many more of his predecessors had been delivered. If the siege had been conducted from the land side only, his hopes might have been justified, for the Danes and English of the Varangian Guard beat back the assault of the Franks on the land-wall. But Alexius III., unlike earlier emperors, was attacked by a fleet to which he could oppose no adequate naval resistance. Though the Crusaders were driven off on shore, the Venetians stormed the sea-wall, by the expedient of building light towers on the decks, and throwing flying bridges from the towers on to the top of the Byzantine ramparts. The blind Doge pushed his galley close under the wall, and urged on his men again and again till they had won a lodgment in some towers on the port side of the sea-wall. The Venetians then fired the city, and a fearful conflagration followed. Hearing that the enemy was within the ramparts, the cowardly Alexius III. mounted his horse and fled away into the inland of Thrace, leaving his troops, who were not yet half beaten, without a leader or a cause to fight for. The garrison bowed to necessity, and the chief officers of the army drew the aged Isaac II. out of his cloister prison and proclaimed his restoration to the throne. They sent to the Crusading camp to announce that hostilities had ceased, and to beg Prince Alexius to enter the city and join his father in the palace.