But it was in the sieges of the city by the Turks that this portion of the walls was attacked most fiercely, as well as defended with the greatest heroism. Here in 1422 Sultan Murad brought cannon to bear, for the first time, upon the fortifications of Constantinople. His fire was directed mainly at an old half-ruined tower beside the Lycus; but the new weapon of warfare was still too weak to break Byzantine masonry, and seventy balls struck the tower without producing the slightest effect.[376] In the siege of 1453 this portion of the walls was assailed by Sultan Mehemet himself with the bravest of his troops and his heaviest artillery, his tent being pitched, as already stated, about half a mile to the west of the Gate of St. Romanus.[377] At the Murus Bacchatareus fought the Emperor Constantine, with his 400 Genoese allies, under the command of the brave Guistiniani, who had come to perform prodigies of valour “per benefitio de la Christiantade et per honor del mundo.” The three brothers, Paul, Antony, and Troilus, defended the Myriandrion, “with the courage of Horatius Cocles.” As the struggle proceeded two towers of the Inner Wall and a large portion of the Outer Wall were battered to pieces by the Turkish cannon. The enemy also succeeded in filling the moat at this point with earth and stones, to secure an unobstructed roadway into the city whenever a breach was effected. On the other hand, Giustiniani repaired the breach in the Outer Wall by the erection of a palisade, covered in front with hides and strengthened on the rear by a rampart of stones, earth, branches, and herbage of every description, all welded together with mortar, and supported by an embankment of earth. Between this barricade and the Inner Wall he furthermore excavated a trench, to replace to some extent the moat which had been rendered useless; and to maintain his communications with the interior of the city he opened a postern in the great wall.