In 1203 these fortifications were attacked by the land forces of the Fourth Crusade.[581] The Venetian fleet, bearing the banner of St. Mark, occupied the Golden Horn, under the command of Dandolo; the army of the expedition under Baldwin held the hill immediately to the west of the Palace of Blachernæ. Upon the walls and towers of the citadel stood the Varangian guards, composed mainly of Englishmen and Danes, loyal to their trust, and the peers of the invaders in courage and strength. Alexius III. and his courtiers watched the scene from the palace windows. At length, on the 17th of July, the Crusaders delivered a grand assault by sea and land; the army attacking the fortress formed by the Walls of Heraclius and Leo; the fleet attempting the adjoining fortifications along the harbour. With the help of ladders, fifteen knights and sergeants scaled the outer Wall, and engaged the defenders on the summit in a desperate struggle. It was a bold attempt, but the odds were too great, and the assailants, leaving two of their number prisoners, were driven off by the swords and battle-axes of the Varangians. Many other Crusaders, also, who had advanced to support the attack, were wounded, and the day went so hard against the Latins at this point that Dandolo, who had captured twenty-five towers of the harbour fortifications, was obliged to abandon the advantage he had gained, and hastened with his ships to protect his worsted allies. Finally, in 1453, the moat before these walls, which had been filled with earth in the course of time, was excavated by the crews of the Venetian galleys present at the siege under the command of Aluxio Diedo. It was made 200 paces long and 8 feet wide, the emperor and his courtiers being present at the work, while two sentries, stationed on the neighbouring hill, watched the Turkish outposts.[582] From the northern extremity of the Heraclian Wall, a short wall was carried to the water’s edge, across the western end of the street that runs along the shore of the Golden Horn, outside the Harbour Walls; thus protecting the latter line of fortifications from attack by the land forces of an enemy. At the same time, for the convenience of traffic, the wall was pierced by a gate, named, from its material, the Xylo Porta (Ξυλόπορτα, Ξυλίνη), the Wooden Gate.[583] It was in its place as late as 1868, and bore an inscription in honour of Theophilus.[584] Very probably, the wall was erected by that emperor when he reconstructed the defences along the harbour. In accordance with its situation, the Xylo Porta is described sometimes as the gate at the northern extremity of the land fortifications;[585] and sometimes as the gate at the western end of the walls along the Golden Horn.[586]