Constantinople - The Citadel at the Gate
by Comer Plummer, III
The art of fortification is a clear reflection of our past. It bears witness to our roots as a race of mutually hostile societies, and impresses upon us the determination of a people to defend themselves. It has existed ever since man first came to realize the value of natural obstacles to his common defense, and evolved as he sought to invoke his own methods to fully exploit this advantage. The building of barriers rapidly evolved from the simple mud parapets and mountain top abodes of the Neolithic Age to the construction of linear and point stone obstacles of the Bronze Age, best represented by the Hittite capital of Hattusas. The Greco-Roman world was the proving ground for medieval fortifications. When, in A.D. 324, Roman Emperor Constantine I moved the capital of the empire from Rome to the sleepy port town of Byzantium, the full possibility of this science was at hand. The results of what followed shaped the course of world history.
Located on a horn-shaped peninsula astride the Bosphorus and the Sea of Marmara, Constantinople dominated the narrow waterway that divides Europe from Asia. The complexities of this geography provided both advantages and challenges to the defense. A steep and rugged shoreline and the swift currents of the Sea of Marmara protected the southern coast. To the north, the Golden Horn, an inlet that bordered the peninsula, was a natural anchorage and harbor. The ancient Lycus River ran diagonally northwest to southeast across the peninsula, forming a narrow valley that sectioned the city into two distinct areas - a chain of six hills running along the Golden Horn to the north, and a single, larger hill to the south. A coherent urban defense had to address these considerations. For the most part, the many leaders and builders of the city succeeded in mastering the terrain. The ruins that still enclose Istanbul are the remnants of centuries of evolution. Awe inspiring even in decay, they are a testament to the glory of Greco-Roman military art.
The despair of her enemies, the walls of Constantinople were the most famous of the medieval world, singular not only in scale, but in construction and the design and integration of the defense with natural obstacles. The principal composition of the walls was mortared rubble, faced with blocks of fitted limestone, and reinforced by courses of layered red brick. To enhance the integrity of the overall network, the towers and walls were built independently of one another. The entire city was enclosed in a defensive circuit of 14 miles of walls, reinforced by 300 towers and bastions, and several strong points and fortresses. The strongest construction faced west, against an approach by land. Here, along a 4-mile stretch of rolling land, stands the legendary Theodosian Walls. Here an enemy had to attack a linear obstacle of four belts, each ascending above the other, with a depth of some 200 feet.
The main line of defense was the Inner Wall, 40 feet in height, 15 feet thick, with a battlemented parapet of 5 feet high, which was accessed by stone ramps. Along its course run 96 massive towers, at intervals of 175 feet, each once capable of mounting the heaviest military engines of the day. A second, Outer Wall of approximately 30 feet in height is joined to this main wall by an elevated 60-foot terrace. The Outer Wall is equipped with 96 bastions, each offset from the towers of the Inner Wall so to avoid masking their fires. Subterranean passages run from many of these points back toward the city, avenues that presumably provided the secure movement of troops to and from a threatened area. The belts were constructed at a tiered elevation, starting at 30 feet for the Inner Wall and descending to the moat. This, and the distance between strong points, ensured that an attacker, once within the network, was in range from all immediate points in the defense. From the Outer Wall extended another 60-foot terrace, ending in a 6-foot high parapet. This bordered a great moat of some 60 feet in width and 15-30 feet in depth, supplied by an aqueduct system. To compensate for the rolling terrain, this moat was sectioned by a number of dams, which enabled it to retain an even distribution of water along its length. The five public gates that traversed this moat by way of drawbridges were set narrowly into the walls and were flanked by towers and bastions. Any assault made on the outer gates would be attacking into the strength of the defense. The Land Walls were anchored at both extremities by two great fortresses. Along the Sea of Marmara, the Castle of the Seven Towers secured the southern approach, while in the north, along the Golden Horn, the salient that was the quarter of the Blachernae Palace, residence of the later Byzantine Emperors, was gradually transformed into one massive fortress. To these two fortified points were adjoined the Sea Walls, similar in construction to the Outer Wall, of which little remains today.
The Golden Horn posed a certain challenge for the defense, since the five miles of sea walls in this area were comparatively weak, and the calm waters here could provide an enemy fleet safe anchorage. Leo III provided the tactical solution in the form of the famous barrier chain. Made of giant wooden links that were joined by immense nails and heavy iron shackles, in an emergency a ship could deploy the chain across the waters of Golden Horn from the Kentenarion Tower in the south to the Castle of Galata on the north bank. Securely anchored on both ends, with its length guarded by Byzantine warships at anchor in the harbor, the great chain was a formidable obstacle and a vital element of the city’s defenses.
While the Land Walls glorify the name of Theodosius I (408-450), the reigning Roman emperor at the time their construction began, it is to one of history’s dim figures, Anthemius, to whom they owe their genesis. Anthemius, as Prefect of the East, was the head of government for six years during the minority of Theodosius and it was he who conceived and carried out a massive and defining expansion of the city defenses. His vision would provide a durable framework for a citadel the new capital would need to become to weather the challenges that lay ahead. The cornerstone of these new fortifications was a massive land wall, represented by the Inner Wall, built in 413. The Theodosian system was completed in 447 with the addition of an outer wall and moat - a response to a nearly calamity, when a devastating earthquake seriously damaged the walls and toppled 57 towers at the very moment Attila and his armies were bearing down on Constantinople. Over the centuries many emperors improved the city fortifications. Their names can be seen to this day engraved on the stone, roughly thirty of them covering more that a millenium, clearly illustrating the importance of these defenses to the Empire.
Constantinople would weather many challenges. While Attila drew away from the city to pursue an easier prey, others were not so discouraged. The Persians, Avars, Sacracens, Bulgarians, Russians and others in turn tried to take the citadel. Far from a deterrent, Constantinople’s reputation seemed to attract her enemies. As a capital of a mighty empire, and at the crossroads of two continents, Constantinople represented to the early medieval world what Rome and Athens had meant to classical times. The “Queen of Cities”, she was a magnet for pilgrim, trader, and conqueror alike. None were wanting. Over a millenium, the citadel turned back besieging armies seventeen times. With each succeeding onslaught, Constantinople became the final stronghold of Greek civilization. Behind her bulwark in the east, Christendom also took shelter.
Undoubtedly, her greatest hour came in turning back a series of determined Arab attacks during the initial period of Islamic expansion. In 632, the Muslim armies burst forth from the desert confines of the Hejaz and poured forth into the Levant. Benefiting from a power vacuum in the region, the Arab armies made stunning advances. The Byzantine and Sassanid Persian empires, nearly prostrate from 25 years of mutual warfare (fighting which cost the Greeks alone some 200,000 men, an enormous drain of manpower in this age) were unable to hold back the tide. In a little more than a decade the Byzantines were driven from Syria, Palestine, Mesopotamia, and Egypt. The Persians fared worse. Arab armies invaded the Persian highlands and destroyed Sassanid Empire. By 661, the standard of the Prophet reached from Tripoli to India.
On two occasions, from 674 to 677, and again in 717-8, Arab armies besieged Constantinople by land and sea. Superior military organization, the leadership of Leo III (the Isaurian) and the timely intervention of one of history’s most decisive weapons – a medieval napalm dubbed “Greek fire” - enabled the Byzantines to weather the storm. The cost to both sides was high. Byzantium lost most of her territory south of the Taurus Mountains and much of the remainder of the Empire lay devastated. The Arabs lost untold thousands through futile attacks against the defenses of Constantinople, and a series of disastrous defeats on land and sea. Still many more perished of disease and cold before in dire encampments before the Land Walls. Of the 200,000 Muslims who laid siege to Constantinople in 717-718, only 30,000 crossed back into Syria the following year.
The impact of Byzantium’s successful defense against the Muslims cannot be overstated. The defense of Constantinople saved not only the Byzantine Empire from the same fate as Sassanid Persia, but spared a fractured and chaotic Europe a Moslem invasion for another nine centuries. One can only wonder of the consequences for Europe and Christendom had Muslims armies marched unchecked into Thrace in the late Seventh or early Eighth Centuries. Our history may have been quite different. What is certain is that the Muslim tide, broken at it shortest approach, was channeled to Europe via another and much longer axis – North Africa. Crossing the Straits of Gibraltar, a Muslim army of 50,000 traversed Spain, crossed the Pyrenees and penetrated into the heart of France before, overextended, they were finally overcome by Charles Martel at Tours in 732. With its expansion stemmed, the Muslim world turned its energies to internal disputes that splintered the CaIiphate, providing medieval Europe a much-needed period of growth and consolidation.
In the end, the same spirit of ingenuity that created the fortifications of Constantinople would prove their undoing. The weaknesses of the defenses must have been obvious, since a series of attackers beginning with the Avars, had tried to exploit them. Interestingly, the salient problems lay along the strongest point – the Land Walls. At a point just south of the Blachernae quarter, a section called the Mesoteichion, the walls dip sharply into the Lycus Valley, exposing that area to enfilade fires from higher ground on the enemy side. Apparently, the trace of the walls owed itself more to the need accommodate a growing population than a regard for the natural lines of terrain. Another problem was the region of the Blachernae Palace, a neglected salient in the original Land Walls. The fortifications here, while often improved, were never equal to those elsewhere in this area. Finally, the construction of the Sea Walls as a single-wall circuit reflected a reliance on natural obstacles and a navy. As long as the Byzantine Navy commanded the narrows of the Hellespont and the Bosphorus, an attack from this quarter was not feared. This situation changed dramatically after 1071, the year Rum Seljuks inflicted a decisive defeat upon the Greeks at Manzikert. As the Empire passed into decline, the Byzantine emperors could no longer maintain a robust navy, and they gradually fell into a reliance on the protection of friendly maritime powers. As the Byzantine Navy withered, Constantinople lay exposed to an assault from the sea.
The challenge was not long in coming. The first Crusades were a marriage of convenience for a Christendom deeply divided between the rival Catholic and Orthodox churches. During the Fourth Crusade this enmity erupted into open warfare when the Latins sought to exploit one of Byzantium’s many dynastic squabbles. While en route to Palestine, the leaders of the crusade, cash-strapped and never opposed to a little profiteering, took up an offer by Alexius, the son of deposed and imprisoned Byzantine Emperor Isaac II, to restore their throne. In exchange for overthrowing the usurper, Alexius promised 200,000 marks, generous trade concessions and troops for the coming campaign. The deal was struck and on July 17, 1203, the Crusaders attacked Constantinople by land and sea. That night, the usurper, Alexius III, fled and the next day Isaac and his son were crowned co-emperors. Their restoration would be short lived. In January 1204, resentful Byzantine nobles toppled the puppet rulers, and brought a defiant Alexius Ducas Mourtzouphlus to the throne. With no hope of securing Byzantine cooperation in the campaign and little chance of success without it, the Crusaders determined once more to take Constantinople.
The Latins, with a decisive naval advantage, decided to make a major effort at the Sea Walls. To provide an assault platform, they erected siege towers on their ships from which long spars were rigged as a kind of suspended bridge. When the ship approached to within range of the wall or tower to be attacked, the bridge was lowered and the knights would shimmy across. The task of leading such an assault must have been daunting. A knight, grasping for balance moving down a narrow platform high above a ship rolling at anchor, then lifting himself over the parapet, all while evading the arrows and cuts of the defenders, was at the mercy of his circumstances. When the first effort failed, for the second the Latins decided to attack with two ships tied together. This provided a more stable platform and the possibility of assaulting a tower at two points. A witness, Robert de Clari, described how the attackers gained a foothold: “The Venetian who entered first in the tower was on one of these suspended bridges with two knights, and from there, with the aid of his hands and feet, he was able to penetrate the level where the bridge provided access. There he was cut down; it was there that André d’Urboise penetrated in the same way when the ship, tossed by the current, touched the tower a second time.”
The Latins had made the critical penetration. Another witness, Henri de Villehardouin, described how they exploited this success: “When the knights see this, who are in the transports, they land, raise their ladders against the wall, and scale to the top of the wall by main force, and so take four of the towers. And all begin to leap out of the ships and transports and galleys, helter-skelter, each as best he can; and they break in some three of the gates and enter in; and they draw the horses out of the transports; and the knights mount and ride straight to the quarters of the Emperor Mourtzouphlus.”
Many historians point to the Latin conquest of Constantinople in 1204 as the practical end of the Byzantine Empire. The Empire disintegrated into a number of feudal fiefdoms and rival kingdoms and despots. While the Greeks, who had established a rival kingdom across the Bosphorus in Nicea, returned to reclaim their capital in 1261, they would find it plundered, and most of their territory lost forever. The Fourth Crusade had shattered the citadel of Christendom in the East.
Though treachery and resourcefulness could overcome the strongest of medieval fortifications, it would be the cannon that would render them obsolete. The Hundred Years War witnessed the emergence of this weapon as the decisive instrument of war on land. The Ottoman Turks, a principality that emerged in the late Fourteenth Century as the next great challenge to Byzantium, were in the forefront of this early technology. Mehmet II ascended the Turkish throne in 1451 with a burning desire to succeed where his father had failed 29 years before - capture Constantinople and make it the capital of his empire. By this time the Ottoman Empire had absorbed most of Byzantium and engulfed its capital as it expanded outward from Asia Minor into the Balkans. In his quest, Mehmet would not be limited to traditional methods of siegecraft, for the sultan’s armies had by that time acquired a large numbers of cannon. Armed with this technology, and a superior energy and vision, Mehmet would go further than others in exploring tactical solutions to the defenses of Constantinople.
Reports circulating around the courts of Europe in the winter of 1452-3 spoke of “unprecedented” Turkish preparations for an assault upon the Constantinople. In fact, the Turkish army that appeared before the city on April 6, 1453 was singular in only one respect. With 80,000 soldiers, among them 15,000 of the Sultan’s elite Janissary Corps, Serbian miners, various siege engines, and a fleet of some 300-400 ships, it was a formidable force, though hardly anything the city had not seen many times before. It was artillery, however, that made this a potent threat. Salient was a new generation of massive siege artillery, courtesy of a Hungarian cannon founder named Urban. Abandoning the meager pay and resources of the Byzantines, Urban found in Mehmet an eager sponsor who set him to work casting large caliber cannon to breach the city walls. The Hungarian went about his work with equal enthusiasm, promising the sultan, “the stone discharged from my cannon would reduce to dust not only those walls, but even the walls of Babylon.” The resultant monster cannon was a weapon of terror. It was titanic, requiring 60 oxen and 200 soldiers to haul across Thrace from the foundry at Adrianople. Twenty-seven feet long, 2 ½ feet in caliber, the great cannon could hurl a 1,200-pound ball over a mile. When it was tested, a Turkish chronicler wrote that a warning went out to the Ottoman camp so that pregnant women would not abort at the shock. Its explosions “made the city walls shake, and the ground inside.” The cannon’s size, however, was also its liability. Crewed by 500, it took 2 hours to load and could only fire eight rounds per day. Fortunately for the Turks, Mehmet had many more practical and more proven pieces - 12 large cannon and 18 batteries of 130 of a smaller caliber weapons.
Against traditional siege engines and complimented by adequate land and sea forces, the walls of Constantinople had proven impregnable. Times, however, had changed. The city had never recovered from the sacking by the Latins in 1204. Destitute and depopulated, she seemed resigned to her fate. Despite efforts of Emperor Constantine XI to rally volunteers, few answered the call. To make matters worse, the defenders’ resolve was undermined by deep divisions caused by the Emperor’s decision to re-unify the Orthodox with the Catholic Church as an incentive for its aid against the Turk. The Empire was at the end of its resources. The defense was left primarily to Italian troops. Greeks commanded only two of the nine sectors of the defense. Powder was in short supply and the walls had fallen into disrepair; the overseers had embezzled the funds for their maintenance. The fleet, long the critical arm of the Empire, now consisted of just three Venetian galliasses and twenty galleys.
The few defenders faced a daunting task. Numbering 4,973 Greek soldiers and volunteers and another 2,000 foreigners, they had to defend fourteen miles of city walls and fortifications. With 500 men detailed to defend the Sea Walls, this would have left only one man every four feet at the Outer Land Walls alone. With many of the defenders in this area manning the engines, towers, bastions and other points, this defense was undoubtedly much thinner. The demands on each man grew precipitously as the battle progressed and as casualties, sickness, and desertion reduced their numbers, and substantial breaches appeared in the walls. That this scant force could defend for seven weeks a city that was one of the largest of the medieval world is remarkable and a testament to both these fortifications and the men who defended them.
For weeks Turkish guns battered the Land Walls, in the words of witness Nicolo Barbaro, with a “great deal of cannon fire in the usual way, and such shouting that the very air seemed to be splitting apart”. The high masonry walls were forlorn in this new age of warfare. They were an easy target for long-range enemy guns, and at the same time could not long withstand the recoil of their own cannon mounted upon them. While the monster cannon exploded on its fourth round, killing its builder and many of the crew, the Turks found in technique a more effective way to employ their artillery. Following the advice of a Hungarian envoy, Turkish gunners concentrated their fires against points on the wall and in a triangular pattern - two shots, one each to the base of the a 30-foot section, then a toppling shot to the top center. In this way, the Turks gradually breached sections of the Outer Walls, exposing the Inner Wall, which too began to crumble. The defenders fought off Turkish attempts to assault the inner defenses. At night they crept forward to cobble in the widening holes with rubble and palisades.
If the end was ever in doubt, Mehmet’s solving the problem of the barrier chain made the outcome inevitable. Unable to force a passage through the chain and past the Christian ships, Mehmet resolved to bypass it by hauling his ships overland, behind Galata and into the Golden Horn. To his engineers, who had hauled Urban’s cannon across Thrace, this posed little problem. Using greased windlasses and buffalo teams, the first ships made the trip on the night of April 22. The next morning the defenders awakened to find a squadron of Turkish vessels in the Horn and themselves with another five miles of sea walls to defend. Before the Greeks and their allies could mount an effective attack against this new threat, Mehmet had the Horn sealed to the west, before his ships, by building a floating bridge of giant oil casks and planks. The Christian ships were now bottled up in the Horn between two arms of the Moslem fleet.
The final blow came on May 29, 1453. The Turks attacked three hours before dawn, concentrating their effort on the Mesoteichion and the western half of the Sea Walls along the Horn. After seven weeks of heroic resistance, the defenders had reached the limits of endurance. In any case, their numbers were no longer sufficient to defend the Land Walls, sections of which were now reduced to rubble. A large beach was opened in the walls in the Lycus Valley and the Turks pressed the attack. Barbaro describes the final moments: “One hour before daybreak the Sultan had his great cannon fired, and the shot landed in the repairs which we had made and knocked them down to the ground. Nothing could be seen for the smoke made by the cannon, and the Turks, under the cover of the smoke, and about 300 of them got inside the barbicans.” While the defenders beat back this attack, the next succeeded in infiltrating the Inner Wall. As Turkish soldiers appeared in their rear, the defenders’ nerve finally broke. The collapse was swift. As word rang out that the defenses had been breached, panic ensued. Those who did not take flight were overwhelmed at their posts. Constantine went to a hero’s death, struck down in the final melee near the great breach. A few managed to escape aboard the Christian ships. Most of the survivors, including nearly all of the population, were sold into slavery. After nearly a thousand years, the Byzantine Empire ceased to exist.
Constantinople was reborn as Istanbul, and, as the capital of the Ottoman Empire its fortunes were reversed. Today the many splendors of Istanbul beckon, while the broken, overgrown remnants of its ancient defenses attract little interest. It is pertinent today, as we look upon the tragic history of the Balkans, to recognize the consequences for the West and the implications for the World had it not been for the citadel at the gate of Europe, whose defenses held the East at bay through the long night of the Dark Ages.
Show Footnotes and
George Young. Constantinople (London, Methven Co. LTD, 1926.), p. 64-7
Byron Tsangadas. The Fortifications and Defense of Constantinople (New York: Columbia University Press, 1980), p. 10.
E.S. Creasy. History of the Ottoman Turks, Volume I (London: Richard Bently, 1854), p126.
Ernest and Trevor Dupuy. Encyclopedia of Military History (New York: Harper and Row, 1977), p. 224.
James Bradbury. The Medieval Siege (Suffolk: St. Edmundsbury Press, LTD., 1992), pp 9-12.
Tsangadas, p. 19.
Ibid, p 33.
Billings, p 131.
Ibid, p 134
Bradbury, pp 293-4.
Young, p 80.
Bradbury, p 222.
A.N. Bernardakis. La Prise de Constantinople. (Athens: B.K. Tsaggaris, 1907), p 74.
Nicolo Barbaro. Diary of the Siege of Constantinople (New York: Exposition Press, 1969), p. 51.
Dukas. Decline and Fall of Byzantium to the Ottoman Empire (Detroit: Wayne State University Press, 1975), p 216.
Ibid, p. 219
Barbaro, p 64.
Amicis, Edmond de. Constantinople. New York: Putnam Sons, 1896.
Barbaro, Nicolo. Diary of the Siege of Constantinople. New York: Exposition Press, 1969.
Bernardakis, A.N., La Prise de Constantinople. Athens: B.K. Tsaggaris, 1907.
Billings, Malcolm. The Crusades. New York: Sterling Publishing Co. 1996.
Bradbury, James. The Medieval Siege. Suffolk: St. Edmundsbury Press, LTD., 1992.
Champollin-Figeac, Jaques-Joseph. Histoire de La Perse Paris: Alphone Pigoreau, 1852.
Creasy, E.S. History of the Ottoman Turks, Volume I. London: Richard Bently, 1854.
Dukas. Decline and Fall of Byzantium to the Ottoman Empire. Detroit: Wayne State University Press, 1975.
Dupuy, Ernest and Trevor. Encyclopedia of Military History. New York: Harper and Row, 1977.
Murdock, Victor, Constantinople, the Challenge of the Centuries. New York: Flemming H. Revell Co., 1926.
Nicol, P.M., The End of the Byzantine Empire. London: Edward Arnold. LTD., 1979.
Tsangadas, Bryon. The Fortifications and Defense of Constantinople. New York: Columbia University Press, 1980.
Young, George. Constantinople. London, Methven Co. LTD, 1926.
Vlasto, E.A. Les Derniers Jours de Constantinople. Paris: La Societe Asiatique, 1893.
Copyright © 2009 Comer Plummer, III
Written by Comer Plummer. If you have questions or comments on this article,
please contact Comer Plummer at:
About the author:
Comer Plummer is a retired US Army Officer. He served from 1983 to 2004 as both an
armor officer and Middle East/Africa Foreign Area Officer. He is currently
employed as a DoD civilian and living in Maryland with his wife
Published online: 03/07/2009.
* Views expressed by contributors are their own and do not necessarily represent
those of MHO.