Post-classical history


On 24 May 1203 the fleet left Corfu. The Crusader fleet now headed into the Aegean, stopping at Halkis, where the local authorities submitted to Prince Alexios Angelos. This so encouraged the Crusader leadership that they sent Alexios and several ships to extend his authority over the neighbouring island of Andros, where, however, the locals resisted for some time. These ships then headed northwards to rejoin the rest of the fleet at Abydos in the Dardanelles in mid-June. The local authorities surrendered to prevent their town being looted, so the hungry Crusaders were obliged to forage over a wide area. After leaving the Dardanelles, the Crusader fleet arrived off Agios Stefanos (Yesilköy) just west of Constantinople on 23 June. Rather than coming ashore on the European side, it sailed on the following day past the Princes’ Islands, which Doge Dandolo had suggested as a suitable base, to Chalcedon (Kadıköy) on the Asiatic side of the southern entrance to the Bosporus. There the army disembarked, probably taking over a day to organize itself and exercise the horses. Nicetas seems to indicate that the galleys promptly made for Skoutarion (Üsküdar) where they could cover the disembarkation, but Crusader sources suggest that they remained closer to the transports.

On 26 June the Crusader army marched up the coast while the fleet sailed alongside. Nicetas describes a half-hearted Byzantine resistance on the Anatolian shore: ‘The Romans who appeared on the nearby hills and stood along the shore discharged missiles against the warships, but to no avail… Another contingent kept watch to the north around Damatrys (Samandra)… they made no attempt to attack the enemy forces, and when the latter charged them, they rose up and scattered.’8 The Fourth Crusade now made camp at Skoutarion, facing Constantinople across the narrow Bosporus.

Aware that the initial reason for the diversion of the Fourth Crusade had been a shortage of food, on 2 July Emperor Alexios III offered to feed and finance the Crusaders if they left Byzantine territory. However, the Crusader leaders maintained their support for Prince Alexios Angelos and demanded that the Emperor abdicate. Apparently believing that the people of Constantinople were being kept in the dark about the Prince’s presence, they sent young Alexios with ten galleys close to the city’s seaward walls, where they called upon the Byzantines to rise up in his favour. After rowing back and forth for a while, receiving insults and missiles, the attempt was abandoned.


The Dardanelles narrow to a channel just 2km wide at Lapseki. (Author’s photograph)


Gallipoli was the main naval base defending the Dardanelles, though the few remaining Byzantine warships made no effort to challenge the Fourth Crusade as it sailed past. (Author’s photograph)

Rather than admit that Prince Alexios lacked the support he claimed and accept Emperor Alexios III’s offer of aid, the leaders – now apparently supported by most of the army – chose to press Prince Alexios’ case militarily. The fact that their forces were in an ideal location to attack Galata and the Golden Horn leaves open the possibility that they considered doing so all along. To appreciate the advantages of the Crusader position, the hydrography of the medieval Bosporus must be understood. In July vast quantities of water from the spring thaw in Russia and Ukraine flowed into the Black Sea, through the Bosporus, the Sea of Marmara and the Dardanelles, into the Aegean and Mediterranean. Though the current was at its strongest, it was weaker close to the coasts, and along the western shore facing Üsküdar there was actually a weak, northwards-flowing counter-current, beyond which was a beach suitable for a naval landing.


After sailing into the Bosporus, the Crusader fleet moored at Chrysopolis (Üskudar), from where they had a clear view of the Byzantine capital. (Author’s photograph)


When the Fourth Crusade reached the Bosporus its fleet made landfall on the eastern shore at Chalcedon (Kadıköy). (Author’s photograph)


The suburb of Galata lies on the north side of the entrance to the Golden Horn. From here a floating boom was stretched across the harbour entrance during emergencies. (Author’s photograph)

The standard uissiers, the Mediterranean horse-transports of this period, carried 30 animals, though the majority of warhorses in the Crusader army were transported aboard less-specialized vessels. The horse-transports would have dropped anchor close offshore, been backed up until the stern was grounded, and then made fast with a cable.9 Each vessel would also have required about 50m of shoreline, in addition to which the Crusaders sent boats carrying crossbowmen to clear defenders from the beach. Normal wind conditions at this time of year were also helpful to the Crusaders, usually blowing moderately from the north or north-east.

The galleys and uissiers were boarded early in the morning of 5 July, setting off to the sounds of, ‘trumpets of silver and of brass, as many as an hundred pair of them, and tabours and timbrels in great number’ according to Robert de Clari. Emperor Alexios III had not been idle, sending a substantial force of cavalry and infantry to defend the area. Nevertheless, Byzantine resistance was completely ineffective, and, according to Hugh of St Pol, ‘The Greeks fled before them when they landed and the army came to the Tower of Galata’. Robert de Clari added that the defenders were chased ‘as far as a bridge which stood nigh the end of the city, and above this bridge was a gate, through which the Greeks passed inward and fled into Constantinople’. This was probably a floating causeway over the narrow upper part of the Golden Horn close to the Monastery of Sts Kosmas and Damian.

Unfortified Galata apparently fell at once, its inhabitants largely being non-Byzantine merchant communities. Nevertheless, there was a significant fire on 5 July. Down by the Golden Horn stood a substantial fortification called the Galata Tower, not to be confused with the existing Galata Tower, which is higher up the hill. It served as an anchorage point for the northern end of a floating defensive boom. Rather than assault the boom itself, the Crusaders decided to attack this Galata Tower, which stood approximately on the site of today’s Yalata Camii Serifi mosque. It had a substantial garrison, including Englishmen, Pisans from the resident merchant community, Geneviani (who were probably Genoese) and Dacians (who may have been Hungarians or Kipchaqs).

Once the Crusader cavalry returned from their pursuit, the army reformed while some galleys beached close enough for their stone-throwing machines to bombard the tower, which was also assaulted from the land. This struggle proved fierce but one-sided, and on 6 July the Galata Tower was taken by storm. The Byzantine chronicler Nicetas seems to have observed events from Constantinople, writing: ‘It was a sight to behold the defenders fleeing after a brief resistance. Some were slain or taken alive, and others slid down the chain as though it were a rope and boarded the Roman triremes, while many others lost their grip and fell headlong into the deep’.




A floating chain or boom closed the entrance to the Golden Horn in an emergency, its northern anchorage point being protected by a strongly garrisoned fortification known as the Tower of Galata. After taking control of the suburb of Galata and setting much of it on fire, the Crusaders and Venetians attacked this tower. The Venetians also ran some of their galleys ashore just east so their light ‘siege engines’ could force the Byzantine defenders to keep their heads down.

After a bitter struggle the Crusaders captured the Tower of Galata while some of its garrison escaped across an unstable walkway on top of the floating boom. Others sought refuge in old Byzantine ships, which had been moored alongside the boom, but many are said to have drowned in the Golden Horn. Once inside the Tower of Galata the Crusaders either disconnected or broke the northern attachment of the floating boom, which then drifted away on the current. This enabled the Venetian fleet to enter the Golden Horn and capture or destroy the Byzantine ships they found there.


Once the Venetian fleet broke into the Golden Horn it attacked the Byzantine ships taking shelter there, capturing many, while others ran themselves ashore. (Author’s photograph)

The Crusaders now had command of the northern end of the boom or chain across the Golden Horn. This remarkable device was about 750m long and consisted of a massive iron chain supported by large floating timbers with a flexible walkway on top. A number of Byzantine ships were also moored along its inner side to serve as defensive positions. The Crusaders probably unfastened rather than broke the northern end of the boom after seizing control of the Gatala Tower. A claim that a big ship named theAquila rammed and broke the boom is very unlikely, though Venetian vessels now entered, capturing, burning or driving ashore the Byzantine vessels within the Golden Horn.

Unlike the Ottoman army that conquered Constantinople in 1453, the Fourth Crusade was relatively few in number and its leaders knew that they would have to focus any attacks upon a limited part of the city’s defences. They selected the north-western corner, where the Crusaders could assault the landward walls of the Blachernae Palace while the Venetian fleet attacked the western end of the Golden Horn walls. The Crusaders therefore crossed the Horn on 10 or 11 July, presumably via the bridge previously used by retreating Byzantine troops. Here, according to Nicetas, ‘they met some slight resistance from the Romans around the bridge located nearby and around the place called Trypetos Lithos [Pierced Stone]’.

The Crusaders then made camp and established a siege position facing the Blachernae Palace. According to Nicetas the camp was ‘divided in part into trenches and wooden palisades around a hill… The defenders on the wall could see the raised tents and could almost converse with those within who faced Gyrolimne [a land gate immediately west of the palace].’ Meanwhile, the Venetians erected siege engines and scaling ladders aboard some of their ships.






1 June: Emperor Alexios III attempts to strengthen the defences of Constantinople. About 20 ships are attached to the floating boom across the entrance to the Golden Horn.

2 24 June: Crusader fleet sails from Agios Stefanos. Doge Enrico Dandolo suggests they seize the Princes’ Islands, but he is ignored. The fleet then sails to Chalcedon, where the army lands. Some galleys probably sail to Skoutarion.

3 26 June: The Crusader army marches up the coast and makes camp at Skoutarion while the Venetian ships sail alongside.

4 25–26 June: Byzantine force around Damatrys shadows Crusader army, but scatters when attacked.

5 26 June: Byzantine troops shoot at the Crusader ships.

6 26 June to 2 July: Alexios III assembles his forces north of Galata.

7 2 July: Crusader leaders sail close to the city’s walls in order to display Prince Alexios Angelos, but Byzantines respond with missiles.

8 4 July: Crusader leadership decides to land on beach north of Galata, using prevailing currents and winds.

9 5 July, morning: Venetian war galleys and horse-transports set out, accompanied by rowed craft carrying archers and crossbowmen. Larger sailing transports probably remain close to the Asiatic shore.

10 5 July: Byzantine defenders flee after brief combat and are pursued to nearest bridge over the upper part of the Golden Horn.

11 5 July: Crusaders attack Galata, causing a substantial fire.

12 6 July: Additional Byzantine troops are sent across the Golden Horn to strengthen the Tower of Galata.

13 6 July: The Tower of Galata is assaulted by sea and land, and captured after a bitter struggle.

14 6 or 7 July: Crusaders break or detatch floating boom and Venetian ships enter Golden Horn, capturing or sinking Byzantine vessels.

15 10–11 July: Venetian fleet prepares to attack Golden Horn fortifications of Constantinople.

16 11 July: Crusader army crosses a bridge over Golden Horn, brushing aside a Byzantine blocking attempt. They then make camp near the Monastery of Sts Kosmas and Damian.

17 11 July: Alexios III observes events from ‘apartments of the Empress of the Germans’.

18 12–17 July: Close-range bombardment and counter-bombardment between the Crusaders and defenders, skirmishing between opposing cavalry forces. On 17 July the Crusaders launch a major assault but are repulsed.

19 17 July: Venetians cross Golden Horn to attack fortifications near the Petria Gate and Monastery of Christ Evergetes.

20 17 July, morning: Alexios III leads a major sortie from the St Romanos Gate to threaten the Crusaders‘ right flank.

21 17 July: Byzantine infantry emerge from the Blachernae Palace to face the Crusader camp.

22 17 July: Crusaders draw up into seven battalions, three to face the Emperor while four guard their back and the camp, each having three or four companies of infantry close behind. Able-bodied servants face the Byzantine infantry.

23 17 July: The Count of Flanders and Alexios III advance towards each other. The Count of Flanders and Henry of Flanders then pull back, but the Count of St Pol and Peter of Amiens do not do so, instead advancing towards the Byzantines. The Count of Flanders reverses his withdrawal. Byzantine flanking force rejoins the Emperor. Both armies halt with the main water-supply canal into Constantinople between them.

24 17 July: Alexios III withdraws into the city.

25 17 July: Venetians set fire to buildings inside the Golden Horn walls, then abandon the occupied fortifications.

26 17–18 July: Fire destroys much of north-western Constantinople.

27 Night of 17–18July: Alexios lll flees through Selymbria Gate and heads for Develtum.

28 18 July: Byzantine aristocracy restores Isaac ll Angelosto imperial throne.

29 Night of17–18 July: Crusaders and Venetians refuse to allow Prince Alexios Angelos to leave camp, insisting he is made co-emperor.

30 1 August: Alexios Angelos is crowned as co-Emperor Alexios IV.

31 31 August: Rioting and the Crusaders’ burning of the ‘Mitation’ Mosque results in extensive fires.


The Crusaders arrived outside the Byzantine capital expecting Prince Alexios Angelos to be welcomed by the people, and when he was not they attacked the city, eventually forcing the Byzantines to accept a new ruler.


The ruins of the Blachernae Palace (Tekfur Sarayı) loom over the northernmost corner of the walled city. (Author’s photograph)


The defenders of Constantinople cannot have been surprised by the devices used against their walls in 1203 and 1204, because comparable siege weaponry had been illustrated in their own military manuals. (Vatican Library, Cod. Gr. 1605, Rome)

For about a week the two sides bombarded each other with stone-throwing siege machines, those of the Crusaders reaching the palace and those of the defenders reaching the besiegers’ tents. Nicetas seems to have been particularly shocked by Emperor Alexios III’s lack of action, and the Byzantine defenders do seem to have lacked coordinated leadership rather than courage. In Nicetas’ words, ‘both sides mounted special cavalry charges many times during the day, and knight competed with horseman in the throwing of the javelin with the excitement and zeal wrought by bravery’.

The first major assault was directed against the Blachernae Palace on 17 July, but the Crusaders were defeated, substantial losses being inflicted by Pisans, Englishmen and Danes in Byzantine service. Raimbaut de Vacqueyras was with Boniface of Montferrat’s unit and took part in these early attacks, as recounted in his ‘Epic Letter’:

By the Blachernae, beneath your banner,

I stood armed, like a Brabantine,

With helm and hauberk and stout gambeson.

Raimbaut would also take part in the siege of 1204 and his letter asks the Marquis for a reward for the injury he suffered in that assault:

And I fought beneath the tower in the Petrion,

And there was wounded beneath my armour.10

Robert de Clari was particularly impressed by the siege machines that the Venetians brought to bear:

He [Doge Dandolo] had them take the spars which support the sails of the ships, which were full thirty fathoms in length, or more, and these he caused to be firmly bound and made fast to the masts with good cords, and good bridges to be laid on these and good guards alongside them, likewise of cords; and the bridge was so wide that three armed knights could pass over it abreast. And the Doge caused the bridge to be so well furnished and covered on the sides with sailcloth and other thick stuff, that those who should go up the bridge to make an assault need have no care for crossbow bolts nor for arrows.

Nicetas was similarly impressed, recording that: ‘The ships were covered with ox hides to make them impervious to fire, and the halyards were fashioned into scaling ladders with rungs made of rope and lowered and again raised high by cables bound to the masts… They then engaged the defenders on the towers and easily routed them, since they were fighting from a higher vantage point and discharging their missiles from above.’ This was clearly why the Venetian assault was more successful that the Crusaders’ attack on the landward walls, winning control of 25–30 towers facing the Golden Horn.

In this crisis Emperor Alexios III took drastic action and led a large sortie against the Crusader flank. It proved a tactical success but had an unfortunate impact upon the Byzantines’ already fragile morale. Early on 17 July Emperor Alexios III emerged at the head of a substantial force through the Gate of St Romanos, south of the river Lycus. Nicetas remained unsympathetic: ‘When the opponent’s land forces suddenly beheld this huge array, they shuddered. Indeed, a work of deliverance would have been wrought had the emperor’s troops moved in one body against the enemy, but now the nagging idea of flight and the faintheartedness of those about him thwarted Alexios from what needed to be done.’

Robert de Clari provides a detailed review of the Byzantine force, which consisted of 17 battalions, but exaggerates their numbers. The larger part went to threaten the Crusader encampment and the flank of the Crusader cavalry, who drew up to face the Emperor. A substantial infantry force similarly emerged, to draw up between the fortifications and the Crusader camp. Anticipating a full-scale battle, the Count of Flanders placed his battalion in the vanguard, the second being the men of the Count of Saint-Pol and Lord Peter of Amiens and the third that of Henry of Hainault and the Germans. Each cavalry unit was closely followed by three or four units of ‘infantry sergeants’ from the same country as the horsemen. Meanwhile four other battalions formed a reserve to protect the encampment. Boniface of Montferrat had overall command, and of the first battalion in this rearguard. Next came Count Louis of Blois, the knights of Champagne and the knights of Burgundy. These rearguard battalions had strict orders to stay in place unless the advancing battalions were clearly defeated. Meanwhile every other man, including ‘grooms and kitchen-knaves’, took whatever arms and armour they could find and were arrayed facing the Byzantine infantry.


The northern end of the ancient landward walls of Constantinople were extended in the 12th century to enclose the Blachernae Palace, and incorporated several more modern ideas. (Author’s photograph)



A lance-armed cavalryman pursuing a horse-archer appears in an early 13th-century wall painting, made to look like draperies, in the Crypt of Massenzio, beneath the Basilica of Aquileia on the north coast of the Adriatic. (Author’s photograph)

The confrontation between the Crusader and Byzantine cavalry is described in great detail by Robert de Clari, though his interpretation of the result might be misleading. Apparently the Count of Flanders and Emperor Alexios III advanced towards each other, starting about ‘a quarter of a league’ (about 1km) apart. The battalions of the Count of St Pol and of Henry of Hainault followed with their respective infantry ‘at the tails of the horses’. When the Count of Flanders had advanced ‘full two crossbow shots’ his counsellors warned that he was in danger of being cut off by the other enemy cavalry on his right flank, so he turned back, as did his brother Henry. However, the troops of the Count of St Pol and Lord Peter of Amiens shouted, ‘Lord! Lord! The Count of Flanders turneth back! And since he turned back, he left to you the vanguard. Now let us take it, in God’s name!’ Refusing Baldwin of Flanders’ urgent requests for them to pull back, they continued to advance. This virtually forced Baldwin to do the same, and resulted in a slow and somewhat disorganized Crusader charge by both cavalry and accompanying infantry.


The fortifications where Constantinople’s landward walls join those along the Golden Horn were strengthened several times, not least in the decades before the Fourth Crusade. (Author’s photograph)

Soon the two armies were close enough for archers and crossbowmen to exchange shots. Yet there was still a small hillock between them, which the Crusaders reached first. At this point Emperor Alexios III halted his army and was rejoined by the Byzantine battalions, which had been threatening the Crusader camp. In reality it is more likely that the Crusaders rather than the Byzantines were now ‘dismayed’, being far from their rearguard and palisaded encampment. There was still a ‘great canal’ lying between the armies, this being the conduit that carried drinking water into Constantinople. It was thought dangerous to cross, so the Crusader leaders took council.

In the event, Alexios III decided the outcome by withdrawing into the city’s fortifications. Tactically his sortie had worked. The Venetians had abandoned their gains in order to support the Crusaders but had set fire to buildings next to the Golden Horn walls. This soon got out of control, spreading deep into the built-up area and probably contributing to Alexios III’s decision to pull back. This first fire within Constantinople burned until 18 July and destroyed an estimated 1,250,000m2.

By the end of 17 July the besiegers had suffered heavy casualties with nothing to show for it. However, unknown to them, the disastrous fire and the Emperor’s retreat so enraged Constantinople’s population that Alexios III lost support within the Byzantine aristocracy and army. Taking ‘one thousand pounds of gold and other imperial ornaments made of precious gems and translucent pearls’, Emperor Alexios III fled during the night and headed for Develtum, a fortified town on the Gulf of Burgas. The Byzantine court now reinstated Isaac II, but the Crusaders, surprised by this turn of events, insisted that Isaac II’s son, Prince Alexios, be made co-emperor, and that both rulers did what Alexios had promised months before. Eventually the Byzantines agreed, and on 1 August 1203 he was crowned as Alexios IV. The Fourth Crusade’s diversion looked like a success.

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