Next to St Sophia itself no structure expressed the psychic life of the city’s people as powerfully as the walls. If the church was their vision of heaven, the wall was their shield against the battering of hostile forces, under the personal protection of the Virgin herself. During sieges the constant prayers and the procession of her sacred relics along the ramparts were considered by the faithful to be generally more crucial than mere military preparations. A powerful spiritual forcefield surrounded such actions. Her robe, housed at the nearby church at Blachernae, was accorded more credit for seeing off the Avars in 626 and the Russians in 860 than military engineering. People saw visions of guardian angels on the ramparts and emperors inserted marble crosses and prayers into the outward facing walls. Near the centre point of the wall there is a simple talisman that expresses Constantinople’s deepest fear. It says: ‘O Christ God, preserve your city undisturbed and free from war. Conquer the fury of the enemies.’
At the same time, the practical maintenance of the walls was the one essential public work for the city, in which every citizen was required to help, without exemption. Whatever the state of the Byzantine economy money was always found to patch up the wall. It was sufficiently important to have its own special officials under the overall authority of the impressively named ‘Count of the Walls’. As time and earthquakes shattered towers and crumbled masonry, running repairs were marked by a wealth of commemorative marble inscriptions set into the stonework. They span the centuries from the first reconstruction in 447 to a total renovation of the outer wall in 1433. One of the last dated repairs before the siege expresses the co-operation of divine and human agencies in the maintenance of the city’s shield. It reads: ‘This God-protected gate of the life-giving spring was restored with the co-operation and at the expense of Manuel Bryennius Leontari, in the reign of the most pious sovereigns John and Maria Palaeologi in the month of May 1438.’
Perhaps no defensive structure summarizes the truth of siege warfare in the ancient and medieval world as clearly as the walls of Constantinople. The city lived under siege for almost all its life; its defences reflected the deepest character and history of the place, its mixture of confidence and fatalism, divine inspiration and practical skill, longevity and conservatism. Like the city itself, the walls were always there, and for anyone in the eastern Mediterranean, it was assumed they always would be. The structure of the defences was mature in the fifth century and changed little thereafter; the building techniques were conservative, harking back to practices of the Greeks and Romans. They had no particular reason to evolve because siege warfare itself remained static. The basic techniques and equipment – blockade, mining and escalade, the use of battering rams, catapults, towers, tunnels and ladders – these were largely unchanging for longer than anyone could recall. The advantage always lay with the defender; in the case of Constantinople its coastal position increased that weighting. None of the armies camped before the land walls had ever succeeded in effecting an entry through the multiple defensive layers, while the city always took prudent measures as a matter of state policy to keep its cisterns brimming and its granaries full. The Avars came with an impressive array of stone-throwing machinery but their looping trajectory made them far too puny to breach the walls. The Arabs froze to death in the cold. The Bulgar Khan Krum tried magic – he performed human sacrifices and sprinkled his troops with seawater. Even its enemies came to believe that Constantinople was under divine protection. Only the Byzantines themselves were ever successful in taking their own city from the land, and always by treachery: the messy final centuries of civil war produced a handful of instances where gates were flung open at night, usually with inside help.
There were just two places where the land wall could be considered potentially weak. In the central section the ground sloped down a long valley to the Lycus River and then up the other side. As the wall followed the downward slope, its towers no longer commanded the high ground and were effectively below the level occupied by a besieging army on the hill beyond. Furthermore the river itself, which was ducted into the city through a culvert, made it impossible to dig a deep moat at this point. Nearly all besieging armies had identified this area as vulnerable, and though none had succeeded, it provided attackers with a vestige of hope. A second anomaly in the defences existed at the northern end. The regular procession of the triple wall was suddenly interrupted as it approached the Golden Horn. The line took an abrupt right-angle turn outwards to include an extra bulge of land; for 400 yards, until it reached the water, the wall became a patchwork structure of different-shaped bastions and sectors, which, though stoutly built on a rocky outcrop, was largely only one line deep and for much of its length unmoated. This was a later addition undertaken to include the sacred shrine of the Virgin at Blachernae. Originally the church had been outside the walls. With a typical Byzantine logic it had been held initially that the protection of the Virgin was sufficient to safeguard the church. After the Avars nearly burned it in 626 – the shrine was saved by the Virgin herself – the line of the wall was altered to include the church, and the palace of Blachernae was also built in this small bight of land. Both these perceived weak spots had been keenly appraised by Mehmet when he reconnoitred in the summer of 1452. The right-angle turn where the two walls joined was to receive particular attention.
As they patched up their walls under Giustiniani’s direction and paraded the sacred icons on the ramparts, the people of the city could be pardoned for expressing confidence in their protective powers. Immutable, forbidding and indestructible, they had proved time and again that a small force could keep a huge army at bay until its willpower collapsed under the logistical burden of siege, or dysentery or the disaffection of the men. If the walls were decayed in places, they were still basically sound. Brocquière found even the vulnerable right angle to be protected by ‘a good and high wall’ when he came in the 1430s. The defenders however were unaware that they were preparing for conflict on the cusp of a technological revolution that would profoundly change the rules of siege warfare.
No one knows exactly when the Ottomans acquired guns. Gunpowder weapons probably made their way into the empire through the Balkans some time around 1400. By medieval standards this was a technology travelling at lightning speed – the first written mention of a gun does not occur until 1313, the first pictorial representation dates from 1326 – but by the end of the fourteenth century, cannon were being widely manufactured across Europe. Small-scale workshops for the production of iron and bronze guns mushroomed in France, Germany and Italy and secondary industries developed around them. Saltpetre ‘factories’ sprang up; middlemen imported copper and tin; technical mercenaries sold their skills in metal casting to the highest bidder. In practical terms the benefits of early gunpowder weapons were dubious: field artillery present at the battle of Agincourt beside the longbow made little material difference. The weapons themselves were cumbersome, tedious to prepare, impossible to aim with any accuracy and as dangerous to their crews as to the enemy. However, cannon fire undoubtedly had a psychological effect. King Edward III at Creçy ‘struck terror into the French Army with five or six pieces of cannon, it being the first time they had seen such thundering machines’ and the giant Dutch gun of Philip van Artevelde in 1382 ‘made such a noise in the going as though all the devils of hell had been in the way’. Metaphors of the inferno are common to these early accounts. There was something infernal about the thunderous roar of ‘the devilish instrument of war’: it upturned the natural order of things and stripped the chivalry out of combat. The church placed a ban on the use of fiery compositions for military purposes as early as 1137 and anathematized the crossbow for good measure, but it made little difference. The genie had exploded out of the bottle.
With the exception of sieges, the contribution of artillery to the conduct of warfare was still minimal by 1420, the moment when the Ottomans started to show a serious interest. Pushing into the Balkans, they captured the resources and the crafts
men to begin manufacturing guns of their own. These included foundries and skilled foundry men, copper mines, cutters of stone balls, makers of saltpetre and gunpowder factories. The Ottomans learned fast. They were hugely receptive to new techniques and adept at integrating skilled Christians into their armies and training their own soldiers too. Murat, Mehmet’s father, created the infrastructure for an artillery force, forming a gunnery corps and corps of gun-carriage drivers in the palace army. At the same time, despite a papal edict that outlawed gunrunning to the infidel, Venetian and Genoese merchants shipped weapons across the eastern Mediterranean, and technical mercenaries, keen to sell their skills to the rising sultanate, made their way to the Ottoman court.
Constantinople experienced its first taste of this new capability in the summer of 1422 when Murat laid siege to the city. The Greeks record that he brought huge ‘bombards’ to the walls under the direction of Germans – and that they were largely ineffective: seventy balls struck one tower without inflicting significant damage. When Murat brought guns to another wall twenty-four years later, the story was completely different. In the 1440s Constantine was attempting to protect one of the city’s few remaining provinces, the Peloponnese, from Ottoman incursions and rebuilt a six-mile wall, the Hexamilion, across the Isthmus of Corinth from sea to sea to fence it off. It was a substantial piece of military engineering thought capable of withstanding prolonged assault. Early in December 1446 Murat attacked the wall with long cannon and breached it in five days. Constantine barely escaped with his life.
In between the two events the Ottomans had deepened their knowledge of artillery, and they had done so at a critical moment in the evolution of cannon construction and explosives. Some time in the 1420s a development took place throughout Europe in the manufacture of gunpowder that substantially increased its potency and stability. Up till then it had been the practice to carry the constituent ingredients – sulphur, saltpetre and charcoal – in different barrels and to mix them on site. The resulting powder was slow burning, susceptible to damp and had a tendency to separate out. In the early fifteenth century experimentation revealed that mixing the ingredients into a paste and drying it into preformed cakes that could be broken down into granules as required produced better results. The so-called ‘corned’ powder was faster burning, 30 per cent more powerful and more resistant to atmospheric moisture. A heavy shot could now be projected at a city wall with impressive momentum. By then giant siege guns, up to sixteen feet long and capable of hurling balls well over 750 pounds, had also begun to appear. Dulle Griete, the Great Bombard of Ghent, roared with a noise ‘made by the furies of Hell’ and shattered the walls of Bourges in 1412. At the same time the new powder increased the danger to gunners and affected cannon founding: barrels were built stronger and longer, and there was a move to guns made in one piece, which had to be cast of bronze – and at a huge price differential. A bronze cannon cost three times as much as a forged iron one, but the exponential benefits evidently justified the expense. For the first time since trumpets flattened the walls of Jericho, a significant advantage was handed back to the side besieging a stoutly fortified castle. Fifteenth-century Europe rang to the roar of great siege guns, the shattering of stone balls against stone walls and the sudden collapse of hitherto impregnable bastions.
Packing a cannon with gunpowder
The Ottomans were uniquely placed to take advantage of these developments. The expanding empire was self-sufficient in copper and naturally occurring saltpetre; it acquired the expertise by conquest or purchase and then set up the structures to disseminate it amongst its own army corps. It quickly became proficient in manufacturing, transporting and firing its artillery – and was second to none in the deep logistical requirements of gunpowder warfare. To put an effective cannon battery in the field at a given moment made exceptional demands on medieval supply chains: adequate quantities of stone balls matched in calibre to the barrels and serviceable gunpowder had to coincide with the arrival of the slow-moving guns. The Ottomans sourced men and materials from across the empire – cannon balls from the Black Sea, saltpetre from Belgrade, sulphur from Van, copper from Kastamonu, tin from overseas trade, scrap bronze from the church bells of the Balkans – and distributed them through an overland transport network by cart and camel that was unmatched in its efficiency. Deep planning was a hallmark of the Ottoman military machine and it transferred these talents naturally to the special requirements of the gunpowder age.
So rapid was the Ottoman assimilation of cannon technology that by the 1440s they had evidently acquired the unique ability, widely commented on by eyewitnesses, to cast medium-sized barrels on the battlefield in makeshift foundries. Murat transported gunmetal to the Hexamilion and cast many of his long guns on the spot. This allowed extraordinary flexibility during siege warfare: rather than hauling the finished weapon to the siege, it could be transported more quickly in bits and could be broken up again afterwards if need be. Guns that ruptured in use, as they frequently did, could be repaired and pressed back into service, and in an age when the match between gun calibre and available cannon balls could be uncertain, barrels could be tailor-made to the ammunition available. (This facility reached its logical conclusion during the epic siege of the Venetian city of Candia on Crete in the seventeenth century. After twenty-one years of fighting, the Ottomans had collected 30,000 Venetian cannon balls unusable in their own guns. They cast three new barrels matched to the enemy calibres and fired them back.)
For the Ottomans, the siege gun seemed to answer something particularly deep in the tribal soul: it fed their rooted opposition to defended settlements. The descendants of the steppe nomads had proved their continuous superiority in open battle; it was only when confronted with the city walls of sedentary peoples that military matters became intractable. Artillery offered the possibility of a quick solution to the dangers of long-drawn-out sieges. It immediately attracted Mehmet’s scientific interest as he considered the impregnable walls of the city. Early in his reign he began to experiment with casting large guns.
The Byzantines were also aware of the potential of gunpowder weapons. Within the city they had some medium-sized cannon and handguns, for which Constantine made strenuous attempts to stockpile resources. He was successful in obtaining supplies of gunpowder from the Venetians but the empire was too poor to invest heavily in expensive new weapons. Some time, probably earlier than 1452, there arrived in the city a Hungarian cannon founder called Orban, seeking his fortune at the imperial court. He was one of the growing band of technical mercenaries who plied their trade across the Balkans; he offered the Byzantines his skill in casting large, single-piece bronze guns. The cash-strapped emperor was interested in the man but had few resources to use his skill; he authorized a tiny stipend to detain Orban in the city, but even this was not paid regularly. The luckless master craftsman became increasingly destitute; some time during 1452 he left the city and made his way to Edirne to seek an audience with Mehmet. The sultan welcomed the Hungarian, provided him with food and clothes, and questioned him closely. The ensuing interview was vividly recreated by the Greek chronicler, Doukas. Mehmet asked if he could cast a cannon suitable to project a stone large enough to smash the city walls, and gestured the size of the stone he had in mind. Orban’s reply was emphatic: ‘If you want, I can cast a cannon of bronze with the capacity of the stone you want. I have examined the walls of the city in great detail. I can shatter to dust not only these walls with the stones from my gun but the very walls of Babylon itself. The work required to make the gun, I can fully carry out, but’, he added, keen to limit his guarantee, ‘I don’t know how to fire it and I cannot guarantee to do so.’ Mehmet ordered him to cast the cannon, and declared that he would see to its firing afterwards.
Whatever the details of the actual interview it seems that Orban set to work to create his first great gun some time during the building of the Throat Cutter in the summer of 1452. At about this time, Mehmet must have started to stockpile substan
tial quantities of materials for guns and gunpowder: copper and tin, saltpetre, sulphur and charcoal. He also seems to have sent out the order for masons to produce granite balls in quarries on the Black Sea. Within three months Orban had cast his first great gun, which was lugged to the Throat Cutter to guard the Bosphorus. It was this weapon that shattered Rizzo’s galley in November 1452 and first sent news of Ottoman artillery power rippling through the city. Satisfied with the results, Mehmet now ordered Orban to produce a truly monstrous cannon, double its size – the archetype of a supergun.
The Ottomans were probably already casting guns at Edirne by this time; what Orban brought was the skill to construct the moulds and control the critical variables on a far greater scale. During the winter of 1452, he set to on the task of casting what was probably the largest cannon ever built. This painstaking and extraordinary process was described in detail by the Greek chronicler, Kritovoulos. Initially, a barrel-shaped mould some twenty-seven feet long was constructed of clay mixed with finely chopped linen and hemp. The mould was of two widths: the front compartment for the stone ball had a diameter of thirty inches, with a smaller after-chamber to take the powder. An enormous casting pit had to be excavated and the fired clay core was placed in it with the muzzle face down. An outer cylindrical clay casing ‘like a scabbard’ was fashioned to fit over this and held in position, leaving space between the two clay moulds to receive the molten metal. The whole thing was packed about tightly with ‘iron and timbers, earth and stones, built up from outside’ to support the huge weight of the bronze. At the last moment wet sand would be drizzled around the mould and the whole thing covered over again, leaving just a hole through which the molten metal could be poured. Meanwhile Orban constructed two brick-lined furnaces faced with fired clay inside and out and reinforced with large stones – sufficient to withstand a temperature of 1,000 degrees centigrade – and surrounded on the outside by a mountain of charcoal ‘so deep that it hid the furnaces, apart from their mouths’.
Constantinople: The Last Great Siege, 1453 Page 11