Siege of Thessalonica (1422–1430)

Background

Following the capture of Gallipoli by the Ottomans in 1354, Turkish expansion in the southern Balkans, conducted both by the Ottomans themselves and by semi-independnet Turkish ghazi warrior-bands, was rapid, leading to the capture of Adrianople, the third-most important city of the Byzantine Empire after Constantinople and Thessalonica, in 1369. Thessalonica, defended by Manuel II Palaiologos (r. 1391–1425), also surrendered after a lengthy siege in 1383–1387, along with Christopolis (modern Kavala) and Thracian Chrysopolis.

Initially, the surrendered cities were allowed complete autonomy in exchange for payment of the kharaj poll-tax, but in 1391, following the death of Emperor John V Palaiologos, Manuel II escaped Ottoman custody and went to Constantinople, where he was crowned emperor in succession to his father. This angered Sultan Bayezid I, who proceeded to lay waste to the remaining Byzantine territories. Chrysopolis was captured by storm and largely destroyed. Thessalonica too submitted, possibly after brief resistance, but was treated more leniently: although the city was brought under full Ottoman control, the Christian population, the Church retained most of their possessions, and the city retained its institutions and semi-autonomous status. Thessalonica remained in Ottoman hands until 1403, when, in the aftermath of the disastrous Battle of Ankara against Tamerlane in 1402, Emperor Manuel II sided with Bayezid's eldest son Süleyman in the Ottoman succession struggle and secured the return of Thessalonica, part of its hinterland, the Chalcidice peninsula, and the coastal region between the rivers Strymon and Pineios.

Nevertheless, relations between Thessalonica and Constantinople remained troubled, with the former city's local aristocracy jealously guarding their extensive privileges, which apparently amounted to virtual autonomy; this was part of a wider phenomenon during the last century of Byzantine history, as central authority weakened, but in Thessalonica's case, a tendency of independence from the imperial capital had been evident at least since the Zealot movement of the mid-14th century, and had been reinforced by the autonomous regime of Manuel II in 1382–1387. In 1403, Thessalonica and the surrounding region were given as an autonomous appanage to John VII Palaiologos. After his death in 1408 he was succeeded by Manuel's third son, the Despot Andronikos Palaiologos, supervised, until 1415, by Demetrios Leontares. Thessalonica enjoyed a period of relative peace and prosperity after 1403, as the Turks were preoccupied with their own civil war, but was attacked by the rival Ottoman pretenders in 1412 and 1416. Once the Ottoman civil war ended, the Turkish pressure on the city began to increase again. Just as during the 1383–1387 siege, this led to a sharp division of opinion within the city between factions supporting resistance, if necessary with Western help, or submission to the Ottomans.

First Ottoman attacks and handover of the city to Venice

The eventual victor in the Ottoman civil war, Mehmed I (r. 1413–1421), maintained good relations with the Byzantines, who had supported him, but the accession of Murad II (r. 1422–1451) changed the situation, as John VIII Palaiologos (r. 1425–1448), the heir-apparent and de facto regent for the ailing Manuel II, set up another son of Bayezid, Mustafa Çelebi, as a rival. Determined to extinguish the remnants of the Byzantine state, Murad laid siege to Constantinople from 10 June to 6 September 1422. In June 1422, Bürak Bey, the son of Evrenos, besieged Thessalonica as well, and ravaged its suburbs and the western portion of Chalcidice.

According to the city's metropolitan bishop, Symeon (in office 1416/17–1429), both he and the Despot Andronikos sent repeated pleas for aid to Constantinople, but the imperial government was short of resources and preoccupied with its own problems. At long last, a single unnamed commander was sent to the city, but he brought neither men nor money with him. The commander proposed setting up a common fund of the citizens to support the defence, but this proposal met with vehement opposition, particularly from the wealthy aristocrats, who would naturally have born the brunt of the cost. The common people however also proved unwilling to contribute, and rioted in favour of an accommodation with the Ottomans, when the news spread that they had offered a peaceful settlement, provided that the Despot Andronikos left the city.

At that point, a group of aristocrats persuaded the Despot Andronikos to seek the assistance of the Republic of Venice, an initiative probably taken without consulting Constantinople. In spring 1423, via the Venetian colony of Negroponte, he informed the Venetians of his intention. The only conditions Andronikos attached to his offer were that the property, customs and privileges of the city's inhabitants, their right to trade and come and go freely, and the position of the city's Orthodox Church, were respected, and that Venice would pledge to defend the city against the Ottomans. Pseudo-Sphrantzes claims that Andronikos sold the city for 50,000 ducats, and this statement was often accepted by more recent scholars until the mid-20th century. However, this is not mentioned by any other source, nor is it found in the original documents pertaining to the affair, as shown by the scholars Konstantinos Mertzios and Paul Lemerle. On the other hand, the Venetian envoys appointed to oversee the handover were authorized to provide a sum of between 20,000 and 40,000 aspers from the revenue of the city as a yearly subsidy to Andronikos, should he request it.

The offer arrived in Venice at an opportune time: the election of Francesco Foscari on 15 April 1423 as Doge of Venice had placed a proponent of a more aggressive and unyielding stance against Ottoman expansionism at the head of the Republic, although the majority of the Great Council of Venice was still dominated by the more cautious tendencies of the merchant nobility that ruled the Republic and feared the disruption in trade that open war with the Ottomans would bring. Thessalonica had loomed large in Venetian minds for some time, as Constantinople seemed to be on the verge of falling to the Turks. Thus in 1419, Venice had re-established a consulate in the city, headed by a local Greek, George Philomati, and after his death in 1422 by his brother, Demetrios.

At a session of the Great Council on 7 July, the offer was accepted. Notices were sent to the Venetian colonies in the Aegean Sea—Negroponte, Nauplia, Tinos and Mykonos, and the vassal Duke of Naxos—to prepare ships to take possession of the city, while the Republic's bailo at Constantinople was instructed to secure the assent of Emperor Manuel. A week later Santo Venier and Niccolo Giorgio were named provveditori (plenipotentiary envoys) and tasked with going to Greece and, if the Despot Andronikos were still willing, take over the city and arrange for its defence by hiring mercenaries. After that, Giorgio was to go before the Sultan, inform him of Venice's acquisition of the city and justify it as an expedient to prevent the city from being captured by other Christians. The envoys were also to arrange for peace both between the Sultan and the Republic, as well as between the Sultan and Emperor Manuel. Emperor Manuel evidently gave his assent to the proposal, for on 14 September 1423 six Venetian galleys, accompanied by one Byzantine galley, entered the harbour of Thessalonica. The Venetians were greeted by a jubilant population as saviours. For the Thessalonians, Venetian rule meant not only security from the Turks—some 5,000 Ottoman troops were besieging the city—but also a secure flow of supplies.

Nevertheless, large segments of the population continued to support seeking a settlement with the Ottomans; the writings of Metropolitan Symeon record that a number of inhabitants fled at this time to the Ottomans. This sentiment included even some members of the nobility: the Byzantine historian Doukas records that soon after taking over the city, the Venetians imprisoned four leading aristocrats, led by a certain Platyskalites, for their association with the Ottomans. The four men were exiled, first to Crete, and then to Venice itself and Padua. Only after the fall of Thessalonica in 1430 were the two surviving ones released. The contemporary Venetian Morosini Codex also records a story of a conspiracy—dismissed as "slanderous" by Donald Nicol—led by the Despot Andronikos to hand over the city to the Turks. The plot was allegedly discovered in November 1423, and Andronikos and his supporters were exiled, with the Despot sent to Nauplia in the Morea.

Diplomatic and military events, 1424–1429

The Venetians hoped to secure Ottoman consent to the occupation of Thessalonica, but when the provveditore Giorgi attempted, probably in February 1424, to carry out is mission to the Sultan's court, not only was he unsuccessful, he was also arrested and imprisoned by Murad. The Ottomans refused to accept the handover, considering the Venetian presence illegal on account of their previous right to the city through conquest. The Ottoman attitude was summed up by the reply allegedly given by Murad to Venetian ambassadors seeking peace, as recorded by Doukas:

When news of Giorgio's arrest arrived in Venice, the Great Council decided to replace both him and Venier. The first two choices, Jacopo Trevisan and Fantino Michiel, refused, but in May 1424, Bernardo Loredan was named duke (governor) of the city, with Jacopo Dandolo as captain (military commander), for a two-year term. In the meantime, Venier was instructed to secure the release of Giorgio, as well as recognition from the Sultan of Venetian control over Thessalonica, the surrounding villages, and the fort of Kortiach (Mount Chortiatis). In exchange, he was to offer an annual tribute of 1,000 to 2,000 ducats, as well as distribute annuities to the Sultan's chief courtiers. The same instructions were also given to the new captain-general of the fleet, Pietro Loredan, who sailed for Thessalonica. If, however, he found the city under siege, Loredan was to attack Gallipoli—where he had scored a major victory in 1416—hinder the passage of Ottoman troops over the Dardanelles, and try to stir up opposition to the Sultan among neighbouring rulers.

This set the pattern for the six-year conflict between the Ottomans and Venice over control of Thessalonica. While the Ottomans blockaded and attacked Thessalonica from land, trying to starve it into surrender, the Republic sent repeated embassies to secure recognition of her possession of Thessalonica in exchange for an annual tribute. To back up their diplomatic efforts, the Venetians tried to put pressure on the Sultan, by stirring up trouble along the Ottomans' periphery, sponsoring efforts for an anti-Ottoman Crusade, and sending their fleet to attack Gallipoli. The Ottomans likewise tried to distract Venice by launching raids of their own on Venetian possessions in the Aegean.

The Venetians found a willing ally in the form of Junayd, ruler of the Aydinid principality in western Anatolia. Junayd was a capable and energetic ruler, who tried to form a broader anti-Ottoman alliance including the Karamanids of central Anatolia, and renew the Ottoman civil war by sending another Ottoman prince, Ismail, to Rumelia. Murad also allied himself with Venice's rival, the Republic of Genoa, to blockade the coasts of Junayd's domain and prevent Ismail from setting sail. Junayd was finally subdued in spring 1425, depriving Venice of his assistance. In February 1424, Murad also concluded a peace with the Byzantines, who returned almost all the lands they had gained in 1403 and, reduced to Constantinople and its environs, became tributary vassals to the Ottomans once more.

Efforts at a Crusade on the other hand faltered on the persistent rivalry of Venice and the King of Hungary Sigismund, the protagonist of the failed anti-Ottoman Crusade of Nicopolis in 1396, over possession of Dalmatia. Both Venice and Hungary exploited the momentary Ottoman weakness and the resulting turmoil in the Balkans to expand their territories—Venice in Dalmatia and Albania, Sigismund in Bosnia, Serbia, and Wallachia; Venice seized Zara, Split, and other Dalmatian cities from Hungary between 1412 and 1420, and found itself at war with the Despot of Serbia, Stefan Lazarević (r. 1389–1427 in 1420–1423, forcing the latter to seek the aid of the Ottomans. Although for many years Emperors Manuel II and John VIII and the King of Poland Władysław II Jagiełło, tried to effect a reconciliation between Venice and Sigismund, it was only in 1425, when Murad II, freed from threats to his Anatolian possessions, went to the counter-offensive, that Venice itself recognized the necessity of an alliance with Sigismund. Nevertheless, despite pressure for a rapprochement from Savoy and Florence as well, Sigismund refused. This dispute allowed the Ottomans to bring Serbia and Bosnia back into vassalage, and after Murad stopped Sigismund's advance at the Siege of Golubac in 1428, a truce was arranged between the two powers.

In the meantime, despite the activities of Loredan around Gallipoli, by October 1424 the situation in Thessalonica was so dire that the Great Council had to authorize the dispatch of 150–200 soldiers, as well as supplies and money, to the city. On 13 January 1425, the Venetians decided to equip 25 galleys, an unusually large and expensive number, for the next year; Fantino Michiel was appointed captain-general. The fleet sailed in April, and was tasked both with settling affairs in the Venetian colonies as well as reassure the Thessalonians of Venetian support. Likewise he was instructed to make contact with the Sultan and pledge considerable sums to the Grand Vizier, Çandarlı Ibrahim Pasha, and other members of the Ottoman court, proposing to restore the salt flats that the Sultan had previously controlled, as well as the tribute of 100,000 aspers that the Despot Andronikos had paid; the Venetians refused, however, to allow the Turks in the city to be tried by their own kadi, as had been the case under the Despot Andronikos, and insisted on the reinstatement of customs posts in the city gates. Michiel was also instructed to secure the release of Venetian citizens taken during an Ottoman raid into the Morea the previous March, and re-confirm the previous peace treaty of 1419, including, if possible, the restitution of the Marquisate of Bodonitsa to its ruler, Niccolo III Zorzi.

In July 1425, ten Venetian galleys under Michiel undertook an expedition east along the shores of Macedonia: the Venetians found Ierissos abandoned by its garrison, but full of provisions, which the Venetians loaded onto their ships. After setting fire to the town and five other forts in the vicinity, the fleet moved onto Christopolis. The Venetians found the castle held by a 400-strong force of Ottoman sipahis under a certain Ismail Bey. The first attempt to land, under Alvise Loredan, was repulsed, and only after all the ships mustered their forces were the Venetians able to overcome Ottoman resistance in a four-hour long battle. 41 Turks were killed, including Ismail Bey, and 30 taken prisoner. After strengthening the site with a stone wall and earthworks, and leaving a garrison of 80 foot soldiers and 50 crossbowmen to hold it, the fleet departed. The Turks soon returned with a larger force of 10,000–12,000 men, and after about twenty days, and despite losing some 800 men, the Ottomans stormed the castle. Unable to escape, half the Venetians were killed and the rest taken prisoner. On 21 July Manuel II died, and John VIII formally became Emperor. In response Murad, who was deeply hostile towards John, launched his forces into raids around Thessalonica and Zetouni (Lamia) in Central Greece.

At the same time, the Greeks of Thessalonica sent an embassy to the Great Council to complain of violations of their rights by the duke and captain. Among other things, they insisted that the Venetians fortify Kassandreia on the western Chalcidice, to protect the Kassandra Peninsula from Ottoman raids. In response, Michiel occupied both the fort of Kassandreia, which he refortified and strengthened by the construction of two smaller forts in the area. He also captured the Platamon Castle, on the opposite side of the Thermaic Gulf, by storm, after setting fire to its main bailey as the Ottoman garrison refused to surrender. Platamon was repaired but probably abandoned soon after, for it is not mentioned again. Following Michiel's request, the Great Council sent 200 men from Padua to man Thessalonica and the forts of Kassandreia, and authorized the captain-general to maintain four galleys in the area. From his letters to the Great Council, Michiel was also engaged in negotiations with the Ottomans, as part of which he offered 20,000 aspers a year to the Ottoman governor of Thessaly, Turahan Bey, and to the Grand Vizier. At the same time, according to the Codex Morosini, a pretender claiming to be Mustafa Çelebi arrived in Thessalonica, and gathered a growing following of Turks who considered him to be the true son of Sultan Bayezid. Pseudo-Mustafa launched raids against Murad's forces from the city, but after both Mustafa and the Venetian captain were almost captured during one of these raids, on 3 September the Great Council issued instructions to stop such raids, and keep the gates of the city shut.

In April 1426, Michiel came near to a settlement with the Ottoman governor at Gallipoli, whereby the Republic would keep Thessalonica in exchange for 100,000 aspers a year, the right of disputes between Turks in the city to be settled by their own kadi, and free and untaxed movement of merchants to and from the city. The negotiations foundered again, however, as the Ottomans insisted on their control of Kassandra and Chortiatis, which they intended as springboards for the eventual conquest of the city. At the same time, the Ottomans launched an attack on the city with reportedly 30,000 men, but the presence of five Venetian galleys in the city helped the defenders repel the attack; according to the report of Loredan and Dandolo to the Great Council, 700 crossbowmen manned the walls, and over 2,000 Turks were killed before retreating. On 6 May, a new duke and captain for the city were elected: Paolo Trevisan and Paolo Orio. In July 1426, the new Venetian captain-general, Andrea Mocenigo, was instructed to resume negotiations, but concede to the Ottomans possession of Kassandra and Chortiatis. On the other hand, the peace settlement should be comprehensive, including the Latin lords of the Aegean, who were Venetian citizens and clients. Failing that, Mocenigo was to attack Gallipoli. In August, the Despot of Serbia, Stefan Lazarević, offered his services as mediator. On 28 November, Mocenigo managed to receive Murad's agreement to a peace treaty on the broad lines of the agreement proposed by Michiel, except that Venice would pay an annual tribute of 150,000 aspers and increased annuities for senior members of the Ottoman court, and would surrender Chortiatis. Despite the Republic's desire to conclude a peace treaty, the months and years dragged on without an agreement. Benedetto Emo, appointed ambassador to the Sultan in July 1427 with the express purpose of ratifying the treaty, was replaced in August 1428 by Jacopo Dandolo, who was instructed, if necessary, to offer a further increase of the tribute to 300,000 aspers and a total sum of gifts from 10,000–15,000 ducats and a further 2,000 ducats as annuities, as well as further sums for possession of the environs of Thessalonica, Kassandra, and the salt works. Dandolo did not have any more success than his predecessor: the Sultan demanded of him the surrender of Thessalonica, and when Dandolo replied that he did not have authority to do this, the Sultan had him thrown in prison, where he was left to die.

In early spring 1428, the Ottoman fleet launched a major raid against Venetian possessions in Greece: some 40 to 65 vessels raided the island of Euboea and took about 700 Venetian citizens prisoner, before going on to raid the environs of the two Venetian outposts of Modon and Coron in the southwestern Morea. When news arrived in Venice on 22 April, even though the previous year's guard fleet under Guido da Canal was still abroad, a guard fleet of 15 galleys was authorized to hunt the Ottoman raiders, under Andrea Mocenigo. In the event, the new fleet did not sail until September, after Canal's fleet was defeated at Gallipoli by a coalition of Ottoman and Christian ships. The Ottoman naval threat became particularly acute at this time due to the defection of the Duke of Naxos, Giovanni II Crispo (r. 1418–1433). Although a Venetian citizen and vassal of the Republic, mounting Ottoman pressure on his possessions had forced the Great Council to authorize him to enter into a separate peace treaty with the Ottomans, which Crispo duly did. As a result, Crispo was forced to effectively assist the Turks in their own raids, and ceased signalling the Venetians in Euboea of impending Ottoman raids via beacons. In early March 1429, an Ottoman fleet even appeared before Thessalonica, and captured two Venetian vessels.

According to the Venetian senator Andrea Suriano, Venice spent on average 60,000 ducats per year in this seemingly fruitless conflict, but the Venetians themselves were hesitant to commit their resources fully to Thessalonica; its proximity to the centre of Ottoman power made their ability to retain it doubtful in the long term, while at the same time, closer to home, Venice was pursuing a conflict with the Duchy of Milan over control of northern Italy. The Republic had long tried to avoid declaring war on the Ottomans, but now it had little choice: Dandolo's imprisonment, the increasing Ottoman naval threat (with the open assistance of the Genoese colonies at Chios and Lesbos), in conjunction with the end of their war with Hungary, made clear to the Venetians that the Sultan was preparing to settle the question of Thessalonica by force. As a result, on 29 March 1429, the Great Council voted an official declaration of war against the Sultan, and ordered more ships to be activated to join the fleet.

On 11 May, the pretender Mustafa appeared before the Great Council, and was given a gift of 150 ducats for his services. On 4 June a new duke and captain were elected for Thessalonica, Paolo Contarini and Andrea Donato, after the first three pairs chosen all declined the post, despite the fine attached to refusal; a clear indication of the unwillingness of the Venetian nobles to undertake the unprofitable and perilous task. On 1 July, Mocenigo attacked the Ottoman ships at Gallipoli, but although he led his flagship to break through the palisade protecting the Ottoman anchorage, the other Venetian vessels did not follow, forcing Mocenigo to withdraw with heavy casualties. Even now, however, Venice would not commit ts full force to the conflict: when Suriano, as a proponent of the hawkish faction, proposed to arm a fleet of 14 ships and engage in a more decisive policy against the Ottomans in January 1430, the proposal was voted down, even though it was rather modest and clearly inadequate to force the Sultan to come to terms. Instead, the Great Council instructed the new captain-general, Silvestro Morosini, to seek the mediation of the Byzantine Emperor for a settlement on the lines of the previous agreements.

Aware of their own weakness, the Venetians tried to form alliances with other regional rulers who feared Ottoman expansionism. Taking advantage of the Ottomans' preoccupation with the Siege of Golubac, Ibrahim II of Karaman (r. 1424–1464) had managed to wrest the area of Hamid, and in August 1429, through the mediation of King Janus of Cyprus (r. 1398–1432), the Venetians approached Ibrahim for an alliance against Murad. Likewise the Venetians tried to influence Murad with the threat posed by the ambitions of Tamerlane's son Shahrukh, especially after the latter's defeat of the Kara Koyunlu in September 1429 brought him within striking distance of the Ottomans' Anatolian domains. Taking advantage of Shahrukh's retiring to Azerbaijan to winter, Murad ordered his general Hamza Bey to lead his forces from Anatolia to Europe in February 1430, and sent him against Thessalonica.

Thessalonica under Venetian rule

The agreement was timely, because by the winter of 1426–1427, conditions in the besieged city approached the point of famine: the Thessalonians were forced to subsist on bread alone, and even there the authorities had to request more shipments of wheat from Venice, as supplies were running dangerously low. These conditions of "extreme poverty, death, and destitution" made the Greek population more and more restless, and even those who had formerly welcomed the Venetians began wavering. In addition, the lack of food jeopardized the city's defences, since many of the guards on the walls—who were paid by Venice with wheat instead of cash—defected to the Turks when their rations were not on time. The situation became progressively worse, so that by the time of the final Ottoman attack in 1430, many soldiers had no weapons because they had sold them for food. The privations of the siege led to an exodus of the city's population, as those of the citizens who could sold their possessions and fled to Constantinople, other Venetian-controlled Greek territories, or to the Turks. From a population reported at between 20,000–25,000 to 40,000 by contemporary Italian sources, it is estimated that only 10,000–13,000 were left by 1429/30. The Venetian authorities tried to put a stop to this by prohibiting the inhabitants from leaving the city, outlawing "all sales, mortgages, and transfers of property, both movable and immovable", and even going as far as to destroy the houses and other property, even trees, of people who had left the city hoping to return after the siege was over, as a deterrent to those who remained behind.

Coupled with several instances of arbitrariness, speculation, and profiteering on behalf of the Venetian authorities, these measures helped to further alienate the Thessalonians. By April 1425, a Byzantine church official who had had his family flee the city wrote of the "enslavement of the city by the Venetians", and similar sentiments about Venetian tyranny are echoed in all contemporary Byzantine sources. In their embassy in July 1425, the Thessalonians submitted a list of 21 complaints and demands, including fixed rations of corn for the poor, the lowering of tax dues and suspension of arrears and debt-related punishments for the duration of the siege, since the closing of the gates meant that people could no longer access their fields, which were furthermore destroyed by the Turks. In a session on 23 July 1425, the Great Council acceded to many of their demands and requested of its officials to respect the customs and rights of the citizens and work together with the local council of twelve nobles in the governance of the city.

Nevertheless, as evidenced from the writings of Metropolitan Symeon, the pro-surrender current continued to gain ground among the Thessalonians at this time, as conditions inside the city worsened; during one attack in 1425 or 1426, many citizens, including some of those guarding the walls, fled to the Ottomans. As the historian Apostolos Vacalopoulos put it, the prevailing view quickly became that "since Thessalonica was bound sooner or later to fall into Turkish hands, it would be preferable to surrender peacefully there and then, and so avoid the sufferings which would ensue if the Turks had to take the city by force." It is in this context that the role Metropolitan Symeon became important as a spokesman and leader of the city's populace. Symeon was an ardently Hesychast and anti-Latin prelate who had opposed the handover of the city to the Venetians, fearing their "corrupting" influence. The Metropolitan tried to strengthen his flock's Orthodox identity against both the Latin Venetians and the Muslim Turks, as well as awaken their will to resist, organizing litanies that paraded the city's icon of the Hodegetria, and delivering sermons about the city's successful delivery from previous sieges through the intervention of her patron, Demetrius of Thessalonica. As a result, he emerged as the leading proponent of resistance, and despite his anti-Latin animus, the Venetians considered him "a most loyal servant of the Republic". His death in September 1429 contributed to the increasing demoralization of the city's populace, who considered it an omen of the city's fall.

In summer 1429, the Thessalonians sent a second embassy to Venice, to complain about the restrictions placed on entry and exit from the city, continued violations of their rights, extortion by the Venetian authorities, the poor supply situation, the neglect of repairing the city's fortifications and the lack of military stores, and the fact that some of the Venetian mercenaries were in contact with the Turks outside the walls. On 14 July the Great Council gave mostly reassuring answers to a list of 31 demands, but the increasing dissatisfaction of the Greek population with Venetian rule was evident. The eyewitness John Anagnostes reports that by the winter of 1429, the majority of the population had come to favour a surrender to the Turks. Sultan Murad was aware of the situation inside the walls, and twice sent Christian officers in his service into the city to incite a rebellion against the Venetians. However, as Anagnostes writes, the population was by that time so reduced in number, and divided amongst itself, that no common cause could be made. Furthermore, the Thessalonians were afraid of the Venetians, who had recruited a special force of guards, the Tzetarioi—according to Anagnostes recruited from criminals—who were authorized to kill anyone advocating a surrender.

Fall of the city

Reinforced by Hamza's troops, in March 1430, Sultan Murad led the final assault on the city himself, which fell on 29 March 1430. Details on the siege are provided by a letter sent by the Venetians of Negroponte to Venice on 2 April, after the refugees from the fall of the city arrived there, and the eyewitness account of John Anagnostes. A squadron of three galleys under Antonio Diedo arrived to reinforce the city on 17 March, but to little avail. A muster of the city's available defenders showed that they sufficed to man only one in two or three crenelles, and they were deficient in both armament and morale: news of Murad's approach at the head of an army rumoured to number 190,000 men caused widespread terror among the populace.

The Sultan appeared before the city on Sunday, 26 March, shortly after noon. It appears that he expected the mere appearance of his army to force the city to surrender. In this vein he sent Christian officers to the walls, to call upon the inhabitants to surrender, but they were driven off by arrows from the walls before they had chance to complete their speeches. The Sultan then began preparations to take the city by storm, which lasted for three days. On the 28th, Murad sent another offer of surrender, but this too was rejected. On the same night, a subaltern officer entered the city and informed the Venetian commanders that the Turks had prepared six ships at the Vardar River that intended to destroy the Venetian galleys in the harbour, which had been left defenceless since all available forces were concentrated in manning the city wall. Fearing lest their retreat be cut off, the Venetian commanders ordered Diedo and his men to withdraw from the wall and man the ships and the harbour defences, without notifying the population. In the event, at around midnight, Christians from the Ottoman camp approached the walls and announced that the final assault would take place the next day, not only from land, but also from the sea. The news spread throughout the city and panicked the populace, who spent the night in terrified vigil in the churches. The panic spread further when Diedo's withdrawal to the harbour became known, which appeared to the Thessalonians as if the Venetians were preparing to abandon them and flee. As a result, a number of defenders simply abandoned their positions on the walls and returned to their homes. At dawn on 29 March, the Ottomans launched their attack, under the command of Sinan Pasha, the beylerbey of Rumelia. The main weight of the attack fell on the less well maintained eastern section of the walls, between the Trigonion and the site of the later Heptapyrgion fortress, where the Sultan himself led the attack. The Ottomans carried forward siege engines, ladders, as well as planks, and began undermining the walls. Ottoman archery proved crucial, for the shots were so well-aimed that pinned down the defenders and killed anyone who tried to peer over the battlements. As a result, much of the defenders' return fire was blind, and the defenders began slowly abandoning their positions. Finally, on the fourth hour, the Ottoman troops broke through on multiple points along the wall; according to Anagnostes, the first Ottomans climbed the wall in the eastern section, which had been left almost defenceless. As the civilian population was being massacred, the Venetians fled to the harbour as best as they could—"one in his mantle, the other in his undershirt" in the words of the report to the Great Council—and many managed to escape to Diedo's ships, and thence to Negroponte. Others, however, were less fortunate: the Venetians lost over 270 men from the galley crews alone. A number of senior officials, including the son of duke Paolo Contarini andLeonardo Gradenigo, captain of one of the galleys, also fell. On their return to Venice, the two Venetian commanders of Thessalonica faced charges of negligence and were imprisoned; they were most likely acquitted, however, for by 1432 both were once again active in the Republic's politics.

Following long-standing custom for a city taken by storm, the plundering of the city lasted for three days. Over 7,000 Thessalonians were taken captive to be sold in the slave markets of the Balkans and Anatolia, although many were ransomed by the Despot of Serbia, Đurađ Branković. The city's monuments also suffered heavy damage in the sack, particularly the cathedral of Hagios Demetrios, as soldiers ransacked them for precious objects and hidden treasure; damage which was compounded later when the Sultan ordered marble sections to be stripped from them and taken to his capital, Adrianople, to be used to pave a bath. On the fourth day, Sultan Murad entered the city himself and prayed at the Church of the Acheiropoietos, which became the city's first mosque. The Sultan then proceeded to restore order and took measures to revive the city, evicting the soldiers from the homes they had occupied and returning them to their owners. Only 2,000 of the population had been left after the sack, of whom many soon converted to Islam. The Sultan soon ordered the city repopulated by bringing in Muslim and Christian settlers from other areas of Macedonia. A great number of empty houses were confiscated and given to the settlers, while most of the main churches were converted to mosques. The Turks settled mostly in the upper part of the city, from where they could better control it.

Aftermath

The Venetians were taken by surprise by the city's fall. When Thessalonica fell, the fleet under Morosini was still sailing off the western coast of Greece. Following their customary strategy, they reacted by sending their fleet to blockade Gallipoli and cut off passage of the Dardanelles. However, the Venetians were by now ready to disengage themselves from this profitless venture, and soon instructed Morosini to seek peace. In July, Hamza Bey signed a peace treaty with the Venetians (ratified on 4 September) whereby the Republic recognized its loss of Thessalonica, restored passage of the Dardanelles, and acknowledged, in exchange of an annual tribute of 236 ducats, Ottoman overlordship over Patras in the Morea. In exchange, the Venetians secured the Sultan's recognition of their possessions in Albania: Durazzo, Scutari, and Antivari.