Siege of Candia

Ottoman forces besieged the Venetian-ruled capital city of the Kingdom of Candia (now Heraklion, Crete) from 1648 to 1669. This 21-year siege is one of the longest sieges in history. It ended with an Ottoman victory, but the effort and cost of the siege contributed to the decline of the Ottoman Empire, especially after the Great Turkish War.

Background

In the 17th century, Venice's power in the Mediterranean was waning as Ottoman power grew. The Republic of Venice believed that the Ottomans would use any excuse to pursue further hostilities.

In 1644, the Knights of Malta attacked an Ottoman convoy of sailing ships on its way from Constantinople to Alexandria. They landed at Candia with the loot, which included the former Chief Black Eunuch of the Harem, the kadi of Cairo, among other pilgrims heading to Mecca.

Siege

Initial Phase of the Siege (1646–1650)

Ottoman Investment and City Conditions (1646–1647)

Following the fall of Canea in 1645 and the subsequent surrender of Rettimo on 13 November 1646, the Ottoman armies cleared their rear from potential Venetian counter-attacks. This secured a direct overland line of communication and supply from Canea straight to the capital city of Candia. With the exception of the capital and half a dozen small isolated castles (*castelli*) scattered across Crete, the Ottomans achieved near-total possession of the island, leaving the fortress of Candia as the final Venetian stronghold.

Consequently, the Ottoman forces began concentrating their troops around Candia, significantly tightening the siege ring. The Venetian garrison in the capital stabilized at roughly 10,000 men, and its fortifications were initially well-prepared by the Proveditor-General. However, internal conditions rapidly deteriorated. Famine and plague—exacerbated by the constant movement of military transport ships—heavily depleted the garrison's ranks. Because Ottoman troops had completely surrounded the city by August 1646, it became hazardous and difficult for the Venetians to transport infected citizens and soldiers to the quarantine hospitals located on a nearby island. By August 1646, plague had claimed the lives of numerous officers and over 500 infantrymen.

The defense was further severely hampered by bitter political and personal rivalries among the Venetian commanding officers. This administrative friction was deliberately encouraged by the Venetian Senate, which feared the concentration of excessive military authority in the hands of a single commander. As a result, subordinate officers frequently bypassed the local chain of command to appeal directly to Venice, which paralyzed military initiative within the fortress. By June 1647, the city of Candia was completely invested by Ottoman forces, with thousands of Turkish troops entrenched in the hills just a few miles away.

Military Stalemate and War of Attrition (1648–1650)

The military operations during the late 1640s settled into a predictable and grueling war of attrition. The main line of Ottoman attacks focused on the southern semi-perimeter of the city's fortifications, launching repeated assault waves against the vital *baluardo* (bastions) of Gesu, Santa Maria, and Martinengo, as well as the advanced fort of San Dimitri. Ottoman engineers heavily engaged in underground mining operations in an attempt to breach the massive walls.

By 1649, the continuous pressure began to impact the defenders. The Ottomans erected several artillery batteries on the south and near the coast, allowing them to bombard the southern periphery and shell Venetian naval movements inside Candia's port. Due to a chronic lack of grain, the Venetian cavalry collapsed, enabling Ottoman light infantry to advance dangerously close to the main bastions without fear of cavalry sorties. Sickness further cut into the garrison, the number of functional Venetian cannons dropped to just over a hundred, and the local squadron of five galleys rotted in the harbor due to lack of repairs. Financially, the fortress became a massive drain on the Republic; a single shipment of 70,000 ducats was instantly spent, as Candia required at least 50,000 ducats monthly just for basic soldier salaries and gunpowder, excluding the mounting costs of repairing shattered walls.

A secondary land front developed around the isolated island-fortress in the Bay of Suda. While the Ottoman forces held the entire coastal territory around the bay and subjected the fortress to daily artillery bombardments, they completely failed to capture it. Because Venice maintained absolute naval superiority, the Ottomans could not launch an amphibious assault on the island. Suda remained a secure refuge for Venetian galleys, allowing them to threaten the Turkish overland supply lines running from Canea to Candia. This dynamic created a permanent military stalemate on Crete: the Ottomans maintained absolute superiority on land, while the Venetians held absolute dominance at sea.

By late 1649, the land war at the walls of Candia entered a total standstill, further slowed by massive internal Janissary mutinies over unpaid wages in the Ottoman camp.

Naval Battle's (1647–1649)

Because the siege was locked in a land deadlock, the true focus of the conflict shifted to the sea. The victory was measured not by the number of galleys destroyed, but by whether men and materials reached the Ottoman armies at Candia. The early Venetian naval campaigns were marked by strategic failures due to the passive leadership of Captain-General Giovanni Cappello. Despite Venetian naval superiority, Ottoman convoys repeatedly bypassed the blockades, safely landing thousands of reinforcements at Canea.

Though the energetic Admiral G. B. Grimani replaced Cappello in 1647, the blockade remained porous. In March 1648, the Venetian fleet suffered a catastrophic disaster when a violent storm off the island of Psara destroyed 18–19 galleys and 9 sailing ships, drowning 800 elite sailors, the Captain-General himself, and 24,000 gold ducats of the naval treasury. Despite being reduced to a fraction of its strength, the crippled Venetian fleet managed to repulse an Ottoman attempt to break out of the Dardanelles later that month.

In May 1649, the Venetians scored a major tactical victory at the Naval Battle of Fokea, where Admiral Giacomo Riva cornered an Ottoman fleet inside the harbor, destroying 3 warships, 3 *maone*, and 9 transport vessels under heavy shore fire. However, the victory proved strategically hollow. The bulk of the Ottoman convoy escaped the harbor intact, successfully delivered its massive load of troops and supplies to the siege lines at Candia, and returned safely to the Dardanelles. By 1650, despite isolated naval victories, the Venetian Republic remained entirely unable to sever the main Ottoman line of supply to Crete.

2nd Phase: Years of Quiet (1650-1666)

Numbers, Logistics and Problems

In 1650, the Turks began building the fortress of New Candia. Although it posed no military threat, it housed 4,000 infantry and 800 cavalry. It was a better place to spend the winter than in the trenches, which were prone to flooding from the rain.

The Venetian fortress was an absolute perfection, as confirmed by more than one expert. Its garrison at various times ranged circa 4,000-6,000 men: for example, in 1651, the garrison numbered 5,300, and in 1658, 4,400. However, they suffered losses due to desertion, as the harsh climate and irregular pay made this a common occurrence.

Desertion became even more common, forcing the use of harsh measures, including executions. Wages were irregular, leaving the Venetian soldiers permanently in debt. The Turks cut off all supply lines and deprived them of the island's last reserves of forage and grain.

One proveditor feared that poverty could spark a rebellion. Ottoman siege greatly complicated logistics, leaving Venice with no respite. The number of Turkish troops held at Candia in the 1650s ranged circa 5,000-10,000, but typically numbered 15,000-20,000, not counting several thousand servants, merchants, and laborers. Of these, 65-70% (9,750-14,000 were stationed at Candia, with the remainder stationed at Cretan fortresses such as Rethymno or Kania. The Turks certainly suffered heavy losses due to disease or combat losses, but they also had regular reinforcements of 6,000-7,000 soldiers.

Candia

Siege of Candia (1650–1666)

Early Phase and Garrison Conditions (1650–1656)

Following the initial shock of the war's first years, the siege of Candia degenerated into a grueling war of attrition and a test of logistical endurance rather than tactical genius. Month after month, large-scale military operations within Candia became rare, as a strategy of limited goals dominated both high commands. To disrupt the Ottoman siege lines, the Venetian garrison relied heavily on timely counter-attacks and diversionary sorties against Canea and other Turkish positions. This forced the Ottomans to scatter their troops over a wider area, preventing them from fully concentrating their forces against Candia itself.

The conditions within the besieged city were catastrophic. By November 1650, the Venetian garrison of roughly 6,000 infantry and 500 cavalry had shrunk to fewer than 4,000 effective men due to severe disease and famine. Soldiers were heavily underpaid, often lacking the means to buy basic food, and many deserted to the Ottoman side out of sheer weakness. Due to critical funding shortages, the Venetian commanders frequently neglected maintenance of the city's fortifications and falsified financial record books to maintain an illusion of order.

By 1651, the Ottoman forces immediately surrounding Candia numbered approximately 12,000 men (out of 28,000 on the entire island), though only about 5,000 were active combatants, the rest being merchants and servants. The composition of the Venetian garrison shifted drastically as the siege progressed; unable to recruit enough expensive and climate-unadapted German mercenaries (*Oltremanti*), Venetian recruiters relied increasingly on local Greek soldiers from the Aegean islands, who eventually made up the vast majority of the garrison.

French Intervention and Naval Stalemate (1657–1665)

By the late 1650s, despite the weakened state of the Ottoman forces, the land war in Candia remained in a total stalemate. From 1657 onward, the Ottomans altered their naval strategy to bypass the Venetian fleet. Instead of massive armadas, they began sending supplies to Crete via small, fragmented convoys deployed from various ports across the empire, making a total Venetian trade embargo virtually impossible to enforce. Concurrently, Ottoman naval commanders adopted a highly cautious doctrine, strictly avoiding open engagements and keeping their smaller fleets under the direct protection of coastal fortresses.

A major attempt to relieve the city occurred in 1660, following the Peace of the Pyrenees, when France dispatched an expeditionary force of 4,000 infantry and 200 cavalry under Prince Amerigo d'Este to Crete. Operating alongside the Venetian fleet, the French successfully captured several Ottoman outposts around the Sudha Bay but failed to force the surrender of Canea. The allied force quickly disintegrated due to Turkish reinforcements, leading to the withdrawal of the French auxiliaries in September 1660 and the subsequent death of Prince d'Este on Paros.

Allied Complacency and the 1666 Crisis

In the early 1660s, the land war experienced a temporary lull as European attention and Ottoman resources shifted toward the Austro-Turkish War in Hungary (1663–1664). Believing that the conflict could be resolved through diplomacy, both sides sought to maintain the status quo, which led to widespread complacency among the Venetian leadership. This passive approach resulted in severe tactical negligence. In 1666, the Venetians made no attempt to establish a blockade at the Dardanelles, allowing an uninterrupted flow of Ottoman supplies to Crete. Furthermore, later that year, a massive Ottoman armada of 50 ships successfully landed substantial troops and fresh provisions at Canea completely unhindered by the Venetian navy, setting the stage for the final, brutal phase of the siege.

Chronology

Naval Battle of Fokea: The Venetian fleet defeated the Turks in a naval battle in 1649.

Battle of San Todoro: In 1650, a Venetian raiding party attacked and drove out the Turks. They failed 2 assaults, but in third Fortress was captured by a short time. Then Venetians withdreved because of lack of water and Turks recaptured it.

Naval Battle of Cyclades: In 1651 Venetian fleet defeated the Turkish flotilla near the Cyclades.

Capture of Skiros: In 1652 Venetians captured Island Skiros from Turks.

Siege of Malvasia: In 1653 The Venetians were unable to occupy the city due to strong resistance from the Turkish troops.

Battle of Knin: No major raids were observed until 1654, but that year the Venetians attacked Knin in Dalmatia. Turkish reinforcements inflicted a complete defeat on the besiegers for their daring raid.

Naval Battle of Dardanelles: Ottoman Victory in 1st Dardanelles, defending Bosporus and Venetian withdrev with successful campaign to Crete.

Francesco Morozini raid: In 1655 Francesco Morozini captured Turkish Fortress Volo, and then Grecee Island Eghina, where he captured 27 turkish guns.

Naval Battles of Dardanelles: Venetian victory in 2nd Battle of Dardanelles & 3rd Battle of Dardanelles, defeating Ottoman fleet and capturing Tenedos and Lemnos; De-facto Blockade of Constantinople.

Naval Battle of Chios: In 1657 Venetian fleet defeated Algerian fleet, burning 7 of them.

Naval Battle of Dardanelles: Ottoman victory in 4th Battle of Dardanelles, defeating Venetian fleet and recapture Tenedos and Lemnos.

3rd Phase: The Final Fury (1666-1669)

After nearly a decade of relative military stagnation, the war entered its most violent and destructive phase in 1667 when the Ottoman Grand Vizier Fazıl Ahmed Pasha Köprülü arrived on Crete with tens of thousands of reinforcements, marking the largest Ottoman army ever assembled on the island . To secure the prolonged siege, the Ottomans constructed a massive fortified stone encampment south of the city called Nuova Candia (Inadiye), which included a front-line cannon foundry and shot production facilities to bypass maritime supply lines . The Venetian garrison initially countered this escalation by massing its largest force to date, reaching a peak of nearly 11,000 defenders by autumn 1667, after Provedditore-Generale Luca Francesco Barbaro had taken command of 8,310 regular troops earlier that year .The fighting quickly transformed into an intense war of attrition heavily focused on mine warfare. In July 1667 alone, at least eighty mines were detonated, with subterranean tunneling becoming so dense that contemporary accounts compared the struggle to a feverish contest of "giant moles" . Many sappers (guastadori) perished from accidental detonations and suffocation in the tunnels . By the winter of 1667, heavy autumn rains flooded the trenches and a plague outbreak forced Köprülü to withdraw his main force to Inadiye, leaving only a "skeleton army" in the front lines, which the exhausted Venetians failed to dislodge .

By the spring of 1668, the Venetian garrison had dwindled to between 5,000 and 6,000 available men due to winter attrition and the departure of allied troops . During the summer, the Ottomans launched a massive pincer assault concentrated on the coastal bastions of Sant'Andrea and Sabionera . At Sabionera, which was built on a vulnerable sandy foundation, Ottoman mines blew a breach sixty paces wide into the main wall, though a newly constructed inner bulwark prevented a total breakthrough . The active Ottoman siege force at this time consisted of 5,000 to 6,000 elite Janissaries and roughly 10,000 sappers and laborers .The human toll of 1668 was staggering for the defenders. Over 900 officers and nearly 6,000 infantry and cavalrymen were killed, with another 3,000 wounded—mostly sappers and trench laborers . Due to poor medical conditions and rampant infections in the trenches, even minor wounds proved fatal . To keep the garrison functional, Venice was increasingly forced to rely on the services of ex-prisoners, bandits, and reprieved criminals, reducing the average company size to just 30 or 40 men . While contemporary Venetian reports claimed Ottoman casualties were five times higher in killed and double in wounded, Mason notes these figures were likely exaggerated . Financially, the defense of Candia cost Venice 4,392,000 ducats for this single year .

In mid-1669, substantial international reinforcements arrived. In May and June, 4,000 German mercenaries reached the city, including 2,400 troops from Brunswick-Lüneburg and 1,600 from Bavaria . They were followed on June 19 by a massive French fleet under the Duke of Beaufort, bringing over 6,000 French infantry and cavalry with months of independent provisions, raising the total garrison to a brief peak of 15,000 to 16,000 defenders . However, tactical friction and French arrogance (hauteur) toward the Venetian and German defenders quickly fractured the alliance . On June 24, a premature and uncoordinated French night sortie at Fort San Demetri turned into a disaster when an accidental powder explosion caused panic, resulting in hundreds of French casualties and the death of the Duke of Beaufort . A subsequent joint allied naval bombardment on July 24 failed when the French flagship Theresa exploded after a direct hit to its magazine, killing 286 crew members and causing the allied fleet to retreat in panic .As summer heat intensified and disease spread through the foul air of the city, the demoralized French troops secretly evacuated to their ships . On August 21, despite desperate pleas from Venetian commanders and local citizens, the Duke de Navailles abruptly withdrew the vast majority of the French contingent . This sparked a domino effect; newly arrived reinforcements under the Duke della Mirandola refused to disembark, while Papal, Maltese, and Savoyard forces abandoned the city under cover of darkness on August 31 .

Capitulation of Candia

Following the allied desertion, Francesco Morosini was left with fewer than 4,000 combat-capable men to defend a four-mile perimeter . Despite successfully repelling a final massive Ottoman assault in early September, Morosini realized further defense was impossible and initiated secret peace talks . Capitalizing on the Grand Vizier's own exhaustion and by skillfully concealing the true, desperate state of the garrison, Morosini bluffed his way into highly favorable surrender terms . Under the final agreement, Venice paid no indemnity or tribute, retained all artillery inside Candia, and secured the safety of the remaining population . At the time of evacuation, only 3,754 surviving soldiers and about 4,000 civilians left the ruined "pile of stone" that remained of the city, leaving it entirely desolated as they sailed away .

Proposed biological warfare attack

Data obtained from the Archives of the Venetian State, relating to an operation organized by the Venetian Intelligence Services, describes a plan aimed at lifting the siege by infecting the Ottoman soldiers with plague; this was to be done by attacking them with a liquid made from the spleens and buboes of plague victims. "Although the plan was perfectly organized, and the deadly mixture was ready to use, the attack was ultimately never carried out." According to a scholar from the USA's National Defense University, information about this planned attack was previously unknown to historians of biological warfare until published in December 2015.

Other participants

Knights of Malta fought at the siege of Candia (in Crete) in 1668
François de Beaufort, who died there
Philippe de Montaut-Bénac, marshal under the duke of Beaufort
Philippe de Vendôme, the nephew of the duke of Beaufort
Vincenzo Rospigliosi, admiral of the fleet and Pope Clement's nephew
Georg Rimpler, German engineer
Charles de Sévigné
Louis de Buade de Frontenac

In fiction

The siege of Candia is an integral part of the background to the historical novel An Instance of the Fingerpost, where a significant protagonist is a Venetian veteran of that siege and several plot developments become clear through extensive flashbacks to the Candia events.

In season 6, episode 3 of the HBO series Silicon Valley, Gilfoyle (incorrectly) states that the Siege of Candia was only ended by use of biological warfare, where the Ottomans were defeated when they became infected with the plague-infested lymph nodes of the dead.

References

The War for Candia, by the VENIVA consortium.
Venice Republic: Renaissance , 1645–69 The war of Candia, by Marco Antonio Bragadin.
The Cretan War – 1645–1669 by Chrysoula Tzompanaki (in Greek).