While the Wall of Heraclius stood alone, it was through the Gate of Blachernæ that Apsimarus was admitted by his adherents, in 698, to supplant Leontius;[[574]] by the same entrance Justinian II., in 705, attempted to force his way into the city to dethrone Apsimarus;[[575]] and through it, again, Theodosius III., in 716, entered and deposed Anastasius II.[[576]] It was before the Heraclian Wall that Crum and Leo the Armenian met to confer, under the circumstances already narrated.
This portion of the fortifications continued to be a favourite point of attack also after the erection of Leo’s Wall. Here, as above stated, the rebel Thomas sought to break into the city in 822;[[577]] here, in 924, Simeon of Bulgaria and Romanus Lecapenus met to conclude peace,[[578]] taking the greatest precautions against the repetition of the treachery which disgraced the former meeting of a Bulgarian king with a Byzantine emperor. In 1047, in the reign of Constantine Monomachus, the rebel general Tornikius took up his position before these walls, and having routed a company of raw recruits who had sallied forth against him by the Gate of Blachernæ, would have rushed into the city with the fugitives, had not the difficulty of crossing the moat given the defenders of the walls time to close the entrance.[[579]]
Through the Gate of Blachernæ the friends of Alexius Comnenus sallied from the city, in 1081, to join the standard of revolt against Nicephorus Botoniates; and it was at the Imperial stables outside the gate that they obtained horses to reach as fast as possible the Monastery of SS. Cosmas and Damianus, baffling pursuit by having taken the precaution to ham-string the animals they did not require.[[580]] In 1097, Godfrey de Bouillon encamped on the hills and plains without these walls. While the negotiations with the crafty Alexius Comnenus were proceeding, the envoys of the Crusaders were on one occasion detained so long by the emperor as to arouse suspicions of treachery on his part; whereupon a band of Crusaders rushed from the camp at the Cosmidion, and in their attempt to enter the city and rescue their comrades set fire to the Gate of Blachernæ.[[581]]
In 1203 these fortifications were attacked by the land forces of the Fourth Crusade.[[582]] 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.[[583]]
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.[[584]] It was in its place as late as 1868, and bore an inscription in honour of Theophilus.[[585]] 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;[[586]] and sometimes as the gate at the western end of the walls along the Golden Horn.[[587]]
Du Cange[[588]] identified the Porta Xylo Kerkou with this gate. But the former was an entrance in the Theodosian lines;[[589]] it led directly into the city, and was built up in the reign of Isaac Angelus[[590]]—facts which did not hold true of the Xylo Porta. Furthermore, Ducas expressly distinguishes the two entrances.[[591]] Or the facts in the case may be stated thus: The Gate of the Xylokerkus was in existence before the erection of the wall in which the Xylo Porta stood; the former entrance being not later than the reign of Anastasius I., in the fifth century, the latter not earlier than the reign of Heraclius, in the seventh century, when the wall on the west of Blachernæ was erected. Therefore the two entrances cannot be the same gate under different names.
In Dr. Mordtmann’s opinion,[[592]] the Postern of Kallinicus (τὸ τῆς Καλλινίκου παραπόρτιον), mentioned by Byzantine writers,[[593]] was the Xylo Porta under an earlier name. And what is known regarding that postern lends support to this view. Like the Xylo Porta, the Postern of Kallinicus stood near the Church of Blachernæ,[[594]] and led to the Church of SS. Cosmas and Damianus in the Cosmidion,[[595]] as well as to the bridge across the head of the Golden Horn.[[596]] The identity is confirmed by the fact that the bridge to which the road issuing from the Xylo Porta conducted was sometimes called the Bridge of St. Kallinicus, after a church of that dedication in its neighbourhood.[[597]]