Where Jonathan Riley-Smith provided an overview of crusading as a movement over many centuries, Jonathan Phillips looks closely at one particular crusade, with an eye toward answering the question of why an expedition intended to take Jerusalem and other sites in the Holy Land wound up instead besieging, conquering and sacking Constantinople. Apparently this was an important question for quite a number of people over a long period of time, but given how many other crusades either strayed far afield from Jerusalem or were directed against fellow Christians in France, Italy, and parts of the German Empire, it’s not all that surprising that at some point crusaders would fight against Byzantium. Indeed, given previous relations between Greeks and crusaders that ranged from grudging passage to active attacks and subversion, it might be more surprising that the two parts of Christendom had not come to blows earlier, not least because they regarded each other as schismatics who had turned away from the true faith and thus, by some measures, worse than actual infidels.
The short version of why the Fourth Crusade wound up at the gates of Constantinople is that one thing led to another, and that choices the leaders made at early stages of the crusade both foreclosed other options and increasingly committed the crusaders to war on the Bosporus. Phillips of course tells a longer version, setting the stage with an overview of crusading in general, what the first three crusades had achieved, and what led to the preaching of a fourth at that particular time. Discussions of the preaching lead naturally into explanations of why leadership fell to men such as the Count of Flanders and the Marquis of Montferrat rather than the kings of England and France. First and foremost, the kings could not set aside their quarrels, even for such a cause as the recovery of Jerusalem. Second, the gap in resources between the prosperous counts and their nominal overlords was not as great in the late 1100s and early 1200s as would later be the case. Regional leaders could mobilize forces for crusades that were as strong as royal contingents. Third, many of these high nobles came from families that had strong crusading traditions, and they thus felt honor-bound to match the deeds of their forbears, or at least to make the attempt.
Two aspects of medieval politics and warfare that come through clearly in The Fourth Crusade are the immense amount of lead time involved and the wild uncertainty. Preparations for a new crusade began soon after the election of Innocent III as pope in 1198; the men of the Fourth Crusade arrived at their rallying point in Venice four years later, in the summer and autumn of 1202. Count Thibaut of Champagne, who had been expected to be one of the leaders of the crusade, died in late May 1201 before he had even mustered his followers, much less begun his way toward the Holy Land. Leaders tried to plan years advance, with little idea of what resources would be available to them, or whether key people would even be alive.
What was probably the most important decision of the Fourth Crusade was taken during this planning period, and changes between the decision and the launch of the crusade set in motion the events that took the Western Europeans to the gates of Constantinople. French leaders agreed that they would go to Jerusalem by way of Alexandria in Egypt. This is not quite as peculiar as it seems at first glance:
In fact, the idea of an invasion of Egypt was, in strategic terms at least, an excellent and familiar solution to the problem of capturing the holy city. There was a long history of the crusaders and the Frankish settlers in the Levant trying to seize Egypt in order to compel the Muslims to surrender Jerusalem. The extraordinary wealth of the Nile Delta and the trade routes from North Africa across to the Middle East would give the Christians unparalleled military and economic strength to bring true stability to their hold on the Holy Land. Furthermore, it would end the Franks’ position as a fragile regional power clinging to the Mediterranean coast and surrounded on almost every landward side by the forces of Islam. If they were to immediately capture Jerusalem, this would be acclaimed as a great triumph and would certainly weaken morale in the Muslim world, but the overall balance of power would simply return to the position created by Saladin before he invaded Jerusalem in 1187. The Muslims and the Franks had long recognized that control of Egypt led to possession of the Holy Land, and a later writer commented that ‘the keys to Jerusalem are to be found in Cairo.’ (p. 67)
It was not such a good idea, however, that the French emissaries who agreed to the plan were willing to publicize it, and the Alexandrian plan remained a secret annex to the treaty with Venice. That treaty proved fateful for the Fourth Crusade. Instead of planning a march through the Balkans and Byzantium on their way to the Levant, western emissaries committed the crusaders to transport by sea, from Venice to the eastern Mediterranean. The Venetians, in turn, committed to joining the crusade and agreed to devote practically all of their resources for a year exclusively to building the crusading fleet. The Venetians would provide the sailors and the ships; the Western Europeans would bring knights and supporters, and would pay an agreed sum to cover the costs Venice incurred in constructing the fleet.
The last item turned out to be crucial for the course of the crusade. Far fewer crusaders arrived at Venice in 1202 than had been expected when the agreement was struck in early 1201. Thibaut of Champagne was dead, sapping momentum from a key region. Other contingents of crusaders made separate arrangements for transportation, sometimes with Venice’s rivals from Pisa or Genoa. Venice had kept its end of the bargain, building an unprecedented fleet to put at the crusaders’ disposal. They took the not unreasonable position that the crusaders should also keep up their side of the treaty, paying the whole of the agreed-upon sum to cover real costs already paid by the Venetians. From that point onward, the interests of Venice played a key role in shaping the trajectory of the crusade.
Philips’ account is also a terrific study in the contingency of history. Had the envoys bargained for a smaller fleet at Venice, they would not have been so deeply in debt to the city-state. Had Thibaut lived, he might have inspired many more French to take up the cross. Had the French reckoned with other groups bypassing Venice, they might have struck a different deal with the doge. Any of these sets of choices would probably have steered the Fourth Crusade away from Constantinople, and to trying its fortunes either in Egypt or the Holy Land.
The immense fleet finally left Venice in October 1202, late in the year to be moving an army around. The goal of that first move was also fateful: Zara, an Adriatic port that had been resisting Venetian control. When it became clear how grave the shortfall of men and money would be, the doge of Venice offered to absolve the crusaders of much of their debt if they would help Venice to take Zara. Helping one Christian power against another was not what the men of northern Europe had taken the cross to do, but the alternative was the collapse of their endeavor. They acquiesced, although not all of the leading crusaders stayed for the siege. When Zara fell in late November 1202, campaigning was over for the winter, and the crusade had advanced barely 150 miles from its starting point.
That winter in Zara, the crusaders made another fateful choice: they received envoys from Prince Alexius Angelos, son of the recently deposed Byzantine emperor. He proposed that if the crusaders would help him regain the throne in Constantinople, he would pay them 200,000 silver marks (well more than what their fleet had cost), that he would provision their army, that he would send 10,000 men with them on their crusade in Egypt, that he would maintain 500 knights in the Crusader States, and that he would end the Great Schism by placing the Orthodox under the authority of Rome. It was an extraordinary offer, but one that deeply divided the crusaders. Phillips describes the dramatic scenes and personal reverses that ended with the crusaders undertaking to support Alexius for a limited time with a promise that after that, they would most definitely head for Syria and Jerusalem.
In fact, the die was cast. Alexius had either overestimated or overstated the amount of support that he enjoyed among the Greeks, and while it was possible for the crusaders to contend that they were restoring a rightful ruler to his place, they were instigating a civil war in the capital of the Empire. Phillips recounts the conflict in colorful but not excessive detail. He shows how Prince Alexius had little support, but the man he sought to supplant — Alexius III — did not have much more, and failed to make the most of the advantages he did possess and eventually fled under cover of darkness leaving the city to the Franks. The prince, now crowned as Alexius IV and co-ruler with his previously deposed father Isaac II, was caught between the promises that he had made to the crusaders and the ability (and willingness) of his subjects to accept his rule and meet those obligations. He slowly turned against the crusaders and they against him. Greek factions turned even more quickly, and one of them murdered Alexius IV, leading to a period of several emperors in a matter of weeks. The crusaders took matters into their own hands, conquered the city, sacked it in a spate of looting that passed into legend, and eventually crowned one of their own as Emperor in the East.
The Fourth Crusade provides a solid overview for a non-expert reader. Phillips draws heavily on contemporary sources, particularly men who were involved with the crusade at both high and low levels. He shows how the crusaders were pulled to Constantinople not as part of any grand design, but as the result of a cascade of decisions and circumstances. He has a fine hand for capturing the dramatic moments of the siege and the improbable nature of the conquest. He makes clear sense of the tangled strands of motivations, and shows how the siege of Constantinople was both surprising and the natural consequence of choices made years before.