The Fall of Constantinople in 1453 and Its Consequences

On the morning of Tuesday 29 May 1453, after nearly two months of siege, the soldiers of Sultan Mehmed II broke through the walls of Constantinople.^⁠[1] Somewhere in the fighting the last Byzantine emperor, Constantine XI, vanished, and with him an empire that had called itself Roman for more than a thousand years. The city had fallen; its story was only beginning. In changing hands, Constantinople also changed the fate of a passage between two seas, and Europe would spend centuries looking for a way to do without it.

April–May 1453

Fifty days before the walls

The work started well before the guns opened fire. On the European shore of the Bosphorus, Mehmed II raised the fortress of Rumeli Hisar, facing Anadolu Hisar on the Asian side.^⁠[2] The order he gave its commander, as the Byzantine chronicler Doukas reports it, left no room for doubt: “Do not allow ships sailing from the Hellespont to the Black Sea or from the Black Sea to the Hellespont, no matter under whose flag they may be sailing.”^⁠[3] The strait had its gatekeeper before the city had its siege.

On 5 April 1453, an hour after daybreak, the Ottoman army drew up before the city. The Venetian Nicolò Barbaro, shut up inside Constantinople, put it at some 160,000 men;^⁠[4] George Sphrantzes, a confidant of the emperor, spoke of 200,000 men and 400 ships.^⁠[1] Chroniclers thought big. Historians today prefer a figure of 60,000 to 80,000 men, which was still overwhelming.^⁠[5]

Behind the walls, the count did not take long. “Our defenders amounted to 4,773 Greeks,” Sphrantzes wrote, “as well as just about 200 foreigners.”^⁠[1] Doukas put the men under arms at 8,000 at most.^⁠[3] The city counted on two defences: its land walls, built in 412–414 under Theodosius II,^⁠[6] and a chain stretched across the Golden Horn, its harbour, to Galata on the far shore.^⁠[3]

Against those walls Mehmed brought a new kind of weapon. Doukas tells its origin as a matter of pay. A Hungarian founder had first offered his services to the emperor, who paid him poorly. He went over to the sultan, and within three months his moulds had produced what Doukas calls “a terrifying and extraordinary monster”.^⁠[3] The Greek historian Kritovoulos describes a mould forty spans long and 1,500 talents of bronze and tin, “as was reported”.^⁠[7] Barbaro notes that one of the guns trained on the gate of St Romanus threw balls of about 1,200 Venetian pounds.^⁠[4] Mehmed later had other giant pieces cast. One of them, the work of the founder Munir Ali, made in two parts that screw together, is now in England.^⁠[8]

That left the harbour chain, which kept the Ottoman fleet out of the Golden Horn. Mehmed got round it in a way nobody expected: overland. On the hill above Galata his men laid slipways covered with timber, about eight stades long, and hauled ships along them into the harbour.^⁠[7] Seventy-two of them according to Barbaro, eighty according to Doukas: fustas and biremes, light enough to be dragged over a hill.^⁠[4]⁠[3] The defenders now had the enemy behind the very chain that was meant to protect them.

The final assault came on 29 May. The fighting lasted “from dawn until noon”, Barbaro writes.^⁠[4] On the walls the Genoese Giovanni Giustiniani, who had come from Genoa with two great ships and his own soldiers and whom the emperor had made protostrator, went down wounded. Kritovoulos says a crossbow bolt struck him in the chest; Doukas, that a lead shot passed through his arm.^⁠[7]⁠[3] Barbaro, no friend of the Genoese, accuses him of deserting his post and running for his ship.^⁠[4]

And the emperor? The witnesses do not agree. Kritovoulos has him fall “in gallant combat”; Doukas says he was cut down like a common soldier by men who did not know who he was; Barbaro passes on a rumour that he had hanged himself.^{⁠[7]⁠[3]⁠[4]} Only one thing is certain. Constantine XI did not outlive his city.

330–1453

The end of an empire, the key to two seas

More than a city fell that day. Dedicated on 11 May 330, Constantinople had been for over eleven centuries the capital of a Christian empire that saw itself as the heir of Rome.^⁠[11] With it went the Byzantine Empire.

For Mehmed II the city was a capital, but above all it was a key. Whoever held Constantinople held the passage between the Black Sea and the Mediterranean. In the words of the historian Albert Lybyer, the capture of 1453 gave the sultan “complete control of the Straits and a commanding position towards Genoa and Venice”.^⁠[12] Turning the Byzantine city into an Ottoman capital would take several more decades.^⁠[2]

Textbooks would later make the date the end of the Middle Ages. That is a convention, popularised in 1688 by Cellarius's school textbook, whose title ran the period a temporibus Constantini magni ad Constantinopolim a Turcis captam: from Constantine the Great to the capture of Constantinople by the Turks.^⁠[13] French universities, for their part, date the start of the modern era to 1492.^⁠[14]

Another picture dies hard: Greek scholars fleeing the city with manuscripts under their arms, off to light the Italian Renaissance. The traffic had started long before. Manuel Chrysoloras was teaching Greek in Florence from 1397, and Bessarion reached Italy in 1437 with the Byzantine delegation to the Council of Ferrara-Florence.^{⁠[15]⁠[16]} After 1453 Bessarion made himself the keeper of the Greek inheritance: the books he gave around 1468 formed the first nucleus of the Marciana library in Venice.^⁠[16] The fall amplified a movement. It did not start one.

1453–1475

The Bosphorus becomes a toll gate

The new master of the straits had no intention of shutting up shop. On 1 June 1453 Galata, the Genoese colony across the water, surrendered in return for a guarantee of lives and property. It lost its autonomy, but Mehmed was keen that it should remain a busy trading port.^⁠[17]

Venice, which carried most of the trade from the East into Europe, opened talks at once.^⁠[12] The treaty of 18 April 1454 guaranteed the Venetians freedom to trade throughout the sultan's lands, by sea and by land, in return for a tax of 2 per cent on their sales; the same rule applied to the sultan's merchants in Venice.^⁠[18] The trading privileges of Genoa and Venice were, in Lybyer's phrase, “renewed with little change”.^⁠[12] The passage stayed open. It simply had a gatekeeper now, and the gatekeeper collected.

Further north, a door was slowly swinging shut. Little by little the Black Sea closed to Italian ships.^⁠[19] Caffa, the great Genoese trading post in Crimea, was besieged as early as 1454; crushed by the tribute imposed on it, it fell to the Ottomans in 1475.^⁠[20] Lybyer adds a caveat: the trade to the East through that sea “was already practically gone”.^⁠[12]

In Europe the news raised the alarm, and it travelled by a very new medium: print. Between 6 and 24 December 1454 a workshop in Mainz printed a small calendar, known today as the Türkenkalender, which the Bavarian State Library attributes to Gutenberg.^⁠[21] Month by month, its twelve poems urge the rulers of Europe to act against the Turks.^⁠[22] The copy that survives is in Munich.^⁠[21]

1478–1517

Getting round the gatekeepers of the East

Over the years the toll grew heavier. In 1478 Venice signed a peace treaty with the sultan that repeated almost word for word those of 1446 and 1454, but now charged it 10,000 ducats a year for its trading privileges, plus 100,000 ducats to be paid within two years.^⁠[23]

One idea long held the field. The Ottomans, it ran, had blocked the spice route, and Europe, starved of pepper, had taken to the ocean to find another. In 1882 the English economist James Thorold Rogers set it down in plain terms: “The fall of Constantinople, beyond doubt, stimulated research into the unknown oceans of the west and south.”^⁠[24] It makes a good story. Historians have since hedged it about with qualifications.

Above all, the Portuguese push had not waited for 1453. Ceuta was taken in 1415, Madeira settled in 1419–1420, the Azores in 1439.^⁠[26] In 1434 Gil Eannes rounded Cape Bojador, and on 18 February 1453, three months before Constantinople fell, the chronicler Zurara finished his account of the discoveries of Henry the Navigator.^⁠[27]

What the sources do support is subtler. The Atlantic powers wanted to get round every middleman in the eastern trade. In the fifteenth century, Lybyer recalls, “the Mameluke sultan and his subjects took toll of all, and Venice did most of the carrying and gained most of the profit”.^⁠[12] By holding the straits and taxing Venetian merchants, the Ottomans added their name to the list of gatekeepers. The fall of 1453 did not start the race for the ocean; it gave the race one more reason. Two voyages would come of it, each of which we tell in its own article: Columbus's to the west, and Vasco da Gama's to India.

And the Ottomans? When they conquered Egypt in 1516 and 1517, they made no attempt to strangle the spice trade. They tried instead to increase its volume, for the revenue it brought.^⁠[28]

1774–2022

The straits, from Mehmed II to the war in Ukraine

To see what Mehmed II won in 1453, a map is enough. By taking Constantinople the Ottomans held the Bosphorus and, with the Dardanelles already in Turkish hands, the whole waterway from the Black Sea to the Aegean.^⁠[29] Once Crimea had been conquered, the Black Sea became what the historian Ahmed Şükrü Esmer calls a “Turkish lake”, closed to foreign shipping, and so it remained until the Treaty of Küçük Kaynarca in 1774.^⁠[29]

With that treaty began a problem that Europe never managed to solve: the question of the Straits.^⁠[30] In 1947 Esmer wrote that it had been “the basis of Turkey's relations with the Powers for almost two centuries”.^⁠[29] It even outlived the Ottoman Empire. In 1946 and 1947 Soviet pressure for bases and transit rights in the straits was among the reasons for the Truman Doctrine.^⁠[31]

The city itself remained the heart of an empire for nearly five centuries. Mehmed II repopulated it, not least by forcibly settling people there from all over the empire,^⁠[32] and at once turned Hagia Sophia into a mosque.^⁠[33] Not until 13 October 1923 did a law of a single article make Ankara the capital of Turkey.^⁠[34] Hagia Sophia, a museum from 1934, changed status once again in 2020, a decision UNESCO said it “deeply regrets”.^{⁠[33]⁠[35]}

The passage, for its part, has been governed since 20 July 1936 by the Montreux Convention. In peacetime it gives merchant vessels “complete freedom of transit and navigation in the Straits, by day and by night, under any flag”,^⁠[36] while warships remain bound by precise limits. Ankara describes it as “one of the rare multi-lateral agreements still in force since it was signed”.^⁠[37]

In 2022 the old treaty returned to centre stage. On 27 February, a few days after Russia invaded Ukraine, the Turkish foreign minister called the situation a “war” and announced that Turkey would apply the convention.^⁠[38] The next day he said he had warned every country, whether it bordered the Black Sea or not, against sending warships through the straits; ships returning to their bases in the Black Sea could still pass, as the text provides.^{⁠[39]⁠[36]} More than five centuries after Mehmed II, which warships may pass is still decided on the shores of the Bosphorus.

The strait that Mehmed locked with two fortresses now sees more than 41,000 ships a year, about 113 a day, according to the Turkish Ministry of Transport.^⁠[40] In 1936 the figure was 17 a day.^⁠[37]

The next link

The Ottomans now held the door to the East, and every passage through it had to be paid for. Before long a navigator would propose avoiding it altogether, by sailing west across the ocean. His name was Christopher Columbus, and his voyage, which we will tell in its own article, is the next link in the chain.