Venetian “Galley of Flanders.” Illustration of a 15th-century trade galley from a manuscript by Michael of Rhodes (1401–1445) written in 1434.

For Byzantine Emperor Constantine XI a successful defense of the city depended on relief from Christian Europe. The endless round of diplomatic missions that preceded the siege had all been undertaken to beg or borrow men and resources for the cause of Christendom. Daily the population looked in the direction of the setting sun for another fleet – a squadron of Venetian or Genoese war galleys, their beaked prows surging up the Marmara to the beating of drums, the rallying of war trumpets, the lion flags of St. Mark’s or the gonfalons of Genoa cracking in the salt wind. But the sea remained ominously empty.

In effect the fate of the city hung on the complex internal politics of the Italian city-states. As early as the end of 1451 Constantine had sent messengers to Venice to report that the city would fall without help. The matter had been debated by the Venetian Senate at length; it was the subject of prevarication in Genoa; in Rome the pope was concerned but required evidence that the union of the churches had been fully implemented. In any case he lacked practical resources to intervene without the Venetians. Genoa and Venice eyed each other in cold commercial rivalry and did nothing.

Constantine’s appeal to the West rested on notions that were religious and medieval, but they were directed at states whose motivations were economic – and surprisingly modern. The Venetians were largely indifferent to whether the Byzantines were unionists or not and had little appetite for the role of defenders of the faith. They were hard-nosed traders, preoccupied with commercial agreements, the security of their sea routes, and the calculation of interest. They worried about pirates more than theology, about commodities rather than creeds. Their merchants studied the price of what could be bought and sold – wheat, fur, slaves, wine, and gold – the supply of manpower for the galley fleets, and the pattern of Mediterranean winds. They lived by trade and the sea, by discount, profit margins, and ready coin. The doge was on excellent terms with the sultan, and trade with Edirne was profitable; furthermore Constantine had considerably damaged Venetian interests in the Peloponnese in the previous twenty years.

It was in this spirit that in August 1452 a minority of senators actually voted to abandon Constantinople to its fate. The lack of concern was modified the following spring as reports trickled in of the throttling of trade routes to the Black Sea and the sinking of Venetian ships. On February 19 the Senate decided to prepare a fleet of two armed transports and fifteen galleys to sail on April 8. The organization of the expedition was entrusted to Alviso Longo with cautious instructions that included a helpful dictat to avoid confrontation with the Ottomans in the straits. He finally departed on April 19, one day after the first major assault on the walls. Others made similarly uncoordinated efforts. On April 13 the government of the Republic of Genoa invited its citizens, merchants, and officials “in the East, in the Black Sea and in Syria” to help with all means the emperor of Constantinople and Demetrios, despot of the Morea. Five days earlier it had been authorizing loans to arm ships against the Venetians. At about the same time the pope had written to the Venetian Senate informing them of his desire to get up five galleys, on loan from the Venetians, for the relief of the city. The Venetians, ever sticklers for a debt, accepted the commission in principle but wrote back reminding the papacy that the cost of galleys for the failed Crusade of Varna in 1444 was still outstanding.

Pope Nicholas had however already undertaken one prompt initiative at his own expense. Fearful of the fate of Constantinople, in March he hired three Genoese merchant ships, provisioned them with food, men, and weapons, and dispatched them to the city. By the start of April they had reached the Genoese island of Chios off the Anatolian coast but could proceed no farther. The north wind that impeded the Ottoman fleet held the Genoese at Chios for a fortnight. On April 15 the wind shifted to the south and the ships set sail. By the 19th they had reached the Dardanelles where they fell in with a heavy imperial transport, laden with a cargo of corn the emperor had purchased from Sicily and commanded by an Italian, Francesco Lecanella. They swept up the Dardanelles and passed the Ottoman naval base at Gallipoli unopposed – the entire fleet had decamped to the Double Columns. The ships were in all likelihood similar to those that had seen off the Ottomans at the boom a few days previously: high-sided sail-powered vessels, probably carracks, described by the Ottoman chronicler Tursun Bey as “cogs.” On the swell of the south wind they made rapid time up the Marmara so that by the morning of April 20 the crews could make out the great dome of St. Sophia forming on their eastern horizon.

The lookout for a relieving fleet was a constant obsession in the city. The ships were seen at about ten in the morning, and the Genoese flags – a red cross on a white background – identified. The news caused an instant stir among the people. Almost simultaneously the ships were also sighted by Ottoman naval patrols, and word was sent to Mehmet in his camp at Maltepe. He galloped down to the Double Columns to deliver clear and peremptory orders to Baltaoglu. Doubtless stung by the failure of his fleet at the boom and the reversal at the land walls, Mehmet gave a message to commander and fleet that was unequivocal: “either to take the sailing ships and bring them to him or never to come back alive.” The galley fleet was hurriedly made ready with a full complement of rowers and crammed with crack troops – heavy infantry, bowmen, and Janissaries from his personal bodyguard. Light cannon were again loaded on board, as well as incendiary materials and “many other weapons: round and rectangular shields, helmets, breast plates, missiles and javelins and long spears, and other things useful for this kind of battle.” The fleet set out down the Bosphorus to confront the intruders. Success was imperative for morale, but this second naval battle was to be fought farther out in the straits where the vagaries of the Bosphorus’s extraordinary winds and local currents were less predictable and the demands on ships could be exacting. The Genoese merchantmen were battering up the straits with the wind astern. The Ottoman fleet, unable to use their sails against the wind, lowered them as they rowed downstream against a choppy sea.

By early afternoon the four ships were off the southeast shore of the city, keeping a steady course for the tower of Demetrios the Great, a prominent landmark on the city’s Acropolis, and well out from the shore, ready to make the turning maneuver into the mouth of the Horn. The huge disparity in numbers filled Baltaoglu’s men “with ambition and hope of success.” They came on steadily, “with a great sounding of castanets and cries towards the four ships, rowing fast, like men wanting victory.” The sound of beating drums and the braying of zornas spread across the water as the galley fleet closed in. With the masts and oars of a hundred ships converging on the four merchantmen, the outcome seemed inevitable. The population of the city crowded to the walls, onto the roofs of houses, or to the Sphendone of the Hippodrome, anywhere that had a wide view of the Marmara and the entrance of the Bosphorus. On the other side of the Horn, beyond the walls of Galata, Mehmet and his retinue watched from the vantage point of an opposing hill. Each side looked on with a mixture of hope and anxiety as Baltaoglu’s trireme drew near to the lead ship. From the poop he peremptorily ordered them to lower their sails. The Genoese kept their course, and Baltaoglu commanded his fleet to lie to and rake the carracks with fire. Stone shot whistled through the air; bolts, javelins, and incendiary arrows were poured up at the ships from all directions but the Genoese did not waver. Again the advantage was with the taller ships: “they fought from high up, and indeed from the yardarms and the wooden turrets they hurled down arrows, javelins, and stones.” The weight of the sea made it hard for the galleys to steady their aim or to maneuver accurately around the carracks still surging forward with the south wind in their sails. The fight developed into a running skirmish, with the Ottoman troops struggling to get close enough in the choppy sea to board or to fire the sails, the Genoese flinging a hail of missiles from their castellated poops.

The small convoy of tall ships reached the point of the Acropolis unscathed and was ready to make the turn into the safety of the Horn when disaster struck. The wind suddenly dropped. The sails hung lifeless from the masts, and the ships, almost within touching distance of the city walls, lost all headway and started to drift helplessly on a perverse countercurrent across the open mouth of the Horn and toward Mehmet and his watching army on the Galata shore. At once the balance shifted from the ships with sails to the galleys with oars. Baltaoglu gathered his larger vessels around the merchantmen at a slight distance and again pelted them with missiles, but with no greater effect than before. The cannon were too light and too low in the water to damage the hulls or disable the masts. The Christian crews were able to put out any fires with barrels of water. Seeing the failure of raking fire, the admiral “shouted in a commanding voice” and ordered the fleet to close in and board.

The swarm of galleys and longboats converged on the cumbersome and disabled carracks. The sea congealed into a struggling mass of interlocking masts and hulls that looked, according to the chronicler Doukas, “like dry land.” Baltaoglu rammed the beak of his trireme into the stern of the imperial galley, the largest and least heavily armed of the Christian ships. Ottoman infantry poured up the boarding bridges trying to get onto the ships with grappling hooks and ladders, to smash their hulls with axes, to set fire to them with flaming torches. Some climbed up anchor cables and ropes; others hurled lances and javelins up at the wooden ramparts. At close quarters the struggle developed into a series of vicious hand-to-hand encounters. From above, the defenders, protected by good armor, smashed the heads of their assailants with clubs as they emerged over the ships’ sides, cut off scrabbling hands with cutlasses, hurled javelins, spears, pikes, and stones down on the seething mass below. From higher up in the yardarms and crow’s nests “they threw missiles from their terrible catapults and a rain of stones hurled down on the close-packed Turkish fleet.” Crossbowmen picked off chosen targets with well-aimed bolts and crewmen deployed cranes to hoist and drop weighty stones and barrels of water through the light hulls of the longboats, damaging and sinking many. The air was a confused mass of sounds: shouts and cries, the roaring of cannon, the splash of armored men falling backward into the water, the snapping of oars, the shattering of stone on wood, steel on steel, the whistling of arrows falling so fast “that the oars couldn’t be pushed down into the water,” the sound of blades on flesh, of crackling fire and human pain. “There was great shouting and confusion on all sides as they encouraged each other,” recorded Kritovoulos, “hitting and being hit, slaughtering and being slaughtered, pushing and being pushed, swearing, cursing, threatening, moaning – it was a terrible din.”

For two hours the Ottoman fleet grappled with its intractable foe in the heat of battle. Its soldiers and sailors fought bravely and with extraordinary passion, “like demons,” recorded Archbishop Leonard begrudgingly. Gradually, and despite heavy losses, the weight of numbers started to tell. One ship was surrounded by five triremes, another by thirty longboats, a third by forty barges filled with soldiers, like swarms of ants trying to down a huge beetle. When one longboat fell back exhausted or was sunk, leaving its armored soldiers to be swept off in the current or clinging to spars, fresh boats rowed forward to tear at their prey. Baltaoglu’s trireme clung tenaciously to the heavier and less well-armed imperial transport, which “defended itself brilliantly, with its captain Francisco Lecanella rushing to help.” In time, however, it became apparent to the captains of the Genoese ships that the transport would be taken without swift intervention. Somehow they managed to bring their ships up alongside in a practiced maneuver and lash the four vessels together, so that they seemed to move, according to an observer, like four towers rising up among the swarming seething confusion of the grappling Ottoman fleet from a surface of wood so dense that “the water could hardly be seen.”

The spectators thronging the city walls and the ships within the boom watched helplessly as the matted raft of ships drifted slowly under the point of the Acropolis and toward the Galata shore. As the battle drew closer, Mehmet galloped down onto the foreshore, shouting excited instructions, threats, and encouragement to his valiantly struggling men, then urging his horse into the shallow water in his desire to command the engagement. Baltaoglu was close enough now to hear and ignore his sultan’s bellowed instructions. The sun was setting. The battle had been raging for three hours. It seemed certain that the Ottomans must win “for they took it in turns to fight, relieving each other, fresh men taking the places of the wounded or killed.” Sooner or later the supply of Christian missiles must give out and their energy would falter. And then something happened to shift the balance back again so suddenly that the watching Christians saw in it only the hand of God. The south wind picked up. Slowly the great square sails of the four towered carracks stirred and swelled and the ships started to move forward again in a block, impelled by the irresistible momentum of the wind. Gathering speed, they crashed through the surrounding wall of frail galleys and surged toward the mouth of the Horn. Mehmet shouted curses at his commander and ships “and tore his garments in his fury,” but by now night was falling and it was too late to pursue the ships farther. Beside himself with rage at the humiliation of the spectacle, Mehmet ordered the fleet to withdraw to the Double Columns.

In the moonless dark, two Venetian galleys were dispatched from behind the boom, sounding two or three trumpets on each galley and with the men shouting wildly to convince their enemies that a force of “at least twenty galleys” was putting to sea and to discourage any further pursuit. The galleys towed the sailing ships into the harbor to the ringing of church bells and the cheering of the citizens. Mehmet was “stunned. In silence, he whipped up his horse and rode away.”

The immediate consequences of the naval engagement in the Bosphorus were profound. A few short hours had tipped the psychological balance of the siege sharply and unexpectedly back to the defenders. The spring sea had provided a huge auditorium for the public humiliation of the Ottoman fleet, watched both by the Greek population thronging the walls and the right wing of the army with Mehmet on the shore opposite.

It was obvious to both sides that the massive new fleet, which had so stunned the Christians when it first appeared in the Straits, could not match the experience of Western seamanship. It had been thwarted by superior skill and equipment, the innate limitations of war galleys – and not a little luck. Without secure control of the sea, the struggle to subdue the city would be hard fought, whatever the sultan’s guns might achieve at the land walls.

Within the city, spirits were suddenly high again: “the ambitions of the Sultan were thrown into confusion and his reputed power diminished, because so many of his triremes couldn’t by any means capture just one ship.” The ships not only brought much needed grain, arms, and manpower, they had given the defenders precious hope. This small flotilla might be merely the precursor of a larger rescue fleet. And if four ships were able to defy the Ottoman navy, what might a dozen well-armed galleys of the Italian republics not do to decide the final outcome? “This unhoped-for result revived their hopes and brought encouragement, and filled them with very favourable hopes, not only about what had happened, but also about their expectations for the future.” In the fevered religious atmosphere of the conflict, such events were never just the practical contest of men and materials or the play of winds, they were clear evidence of the hand of God. “They prayed to their prophet Muhammad in vain,” wrote the surgeon Nicolo Barbaro, “while our Eternal God heard the prayers of us Christians, so that we were victorious in this battle.”