The following is my own translation of ‘Alī ibn al-Athīr’s account of the Fourth Crusade and the conquest of Constantinople by the Crusaders in 1204. It is a significant account because it provides historians with one of the few near-contemporary reflections on the Fourth Crusade from a Muslim perspective, and also because it was written between 1204 and 1261, when Byzantine rule was finally restored in Constantinople. Notably, Ibn al-Athīr makes no reference to the existence of the Despotate of Epiros or the Empire of Trebizond, both Byzantine successor states, and only discusses the polity established by Theodore Lascaris in Nicaea. As such, the last part of the account gives a sense of the political reality in the south-eastern Balkans and north-western Anatolia following the establishment of the Latin Kingdom of Constantinople and makes it clear that, at least as far as Ibn al-Athīr was concerned, the legitimacy of the Empire of Nicaea as a continuation of the Byzantine Empire was firmly established. Moreover, Ibn al-Athīr seems to have a strong understanding of the political system which comprised the Latin Empire of Constantinople, since he does not fail to mention the tripartite division between Venice, Baldwin of Flanders, and Boniface of Montferrat. Ibn al-Athīr’s account is also important because of the details which it provides, most of which can be corroborated by the Latin and Greek accounts.
It is difficult to know with any certainty who Ibn al-Athīr’s main sources for his account actually were. There is no doubt that he would have relied heavily upon Latin and Greek accounts of the event, but it is also possible that he drew upon accounts of Muslims who resided in Byzantine lands (especially those in Constantinople itself) or Seljuk territories. However, due to the fact that there are hardly any direct references within the text, it is difficult to trace the origin of a particular narration.
“In the year 600 A.H. [1204 A.D.], the Franks conquered the city of Constantinople from the Romans and removed the latter from power. The main reason for this was that the Byzantine emperor had married the sister of the King of the Franks, who was one of the greatest rulers of the Franks. This marriage produced a son, but this king was overthrown by his brother [Alexios III Angelos] who blinded and imprisoned him. As a result, this son fled to his maternal uncle [Philip of Swabia] seeking his assistance against his paternal uncle. The former agreed to help him. At this time, many of the Franks had gathered to set out on an expedition to the Levant in order to recapture Jerusalem from the Muslims, and they took this prince with them. They purposely rerouted their expedition towards Constantinople in order to resolve matters between this prince and his paternal uncle [the Byzantine emperor]; the prince had no ambitions for anything more than this. Upon their arrival, the Byzantine emperor assaulted [the Crusaders] with his armies leading to a battle between the two sides which took place on Rajab 599 A.H. [March 1203 A.D.] in which the Byzantines were defeated. The Byzantines retreated into the city of Constantinople and were pursued there by the Franks, leading the Byzantine emperor to flee to the outskirts of his country. It has also been said that the Byzantine emperor did not fight the Franks in an open battlefield, but rather that the latter besieged Constantinople.
Within the city of Constantinople itself, there were certain Byzantines who desired booty, so they set fire to the city, thereby distracting most of the inhabitants and threw open one of the gates of the city. The Franks thus entered the city and the Byzantine emperor fled. As a result, the Franks elevated the young prince [Alexios IV] to the throne—even though he did not exercise any real power—and freed his father from prison; in reality, the Franks were the ones who ruled. They were a burden upon the populace and extorted large sums of money from the people, even stripping the crosses, holy books and icons of Christ (peace be upon him) and the Apostles of their gold and gems. This was too much for the Byzantines to endure and they rose up and killed the emperor, expelled the Franks from the city, and sealed the gates of the city. This all occurred in Jumada I 600 A.H. [January 1204 A.D.]. The Franks then besieged the Byzantines in their city, fiercely waging war against them day and night. After a time, the Byzantines were severely weakened and sought aid from the Sultan Rukn al-Dīn Sulaymān b. Kilīj Arslān [r. 1196–1204 A.D.], the ruler of Konya and other lands, but to no avail.
Constantinople had a significant population of Franks, whose numbers reached perhaps 30,000. They coordinated and collaborated with the Franks who were besieging the city and set fire to the city for a second time, leading to the destruction of about a quarter of it. They then opened the gates of the city for the besiegers, who entered the city and put it to the sword for three days in which the Byzantines were subject to systematic killing and pillage. Almost all the Byzantines were either murdered or impoverished as a result. A group of Byzantine notables had entered the great cathedral known as the [Hagia] Sophia to seek refuge, but were pursued there by the Franks. When some monks, abbots and priests came out of the church, carrying the Bible and crosses in order to beg for mercy, the Franks slaughtered them all before entering the cathedral and plundering it as well.
After the sack of the city, there were three kings: the Doge of Venice, the owner of the powerful fleet, upon whose ships the Franks had come to Constantinople, who was a blind elderly man; another king known as the Marquis [Boniface of Montferrat], who was the most distinguished of the Franks; and the last was known as the Kond Afland [Baldwin, Count of Flanders], who had the most troops under his command and, when they conquered Constantinople they installed him as emperor. And God grants his dominion to whom He wills and removes it from whom He wills! He was made ruler of Constantinople and its neighboring territories, while the Doge of Venice was given the islands, such as Crete, Rhodes and others, and the Frankish Marquis was allotted the territories east of the straits, such as Nicaea and Lydia, but many of these territories remained under Byzantine control and were not conquered by the Franks. The lands that were formerly under Byzantine control east of the straits, including Nicaea, Lydia and the territories neighboring the kingdom of Rukn al-Dīn Sulaymān b. Kilīj Arslān, fell under the domain of one of the most senior Byzantine commanders, known as Lashkārī [Theodore Laskaris], who still controls these territories until the present day.”
[Ibn al-Athīr, al-Kāmil fī al-Tā’rīkh (Beirut: Dar Sader, 2008), Vol. 12, pp. 190–192]. For a Byzantine chronicle of the sack of Constantinople, see: http://www.fordham.edu/halsall/source/choniates1.asp