Probably the most telling event which displayed the decline of the crusader ideal was the capture and pillage of the Christian bastion of Constantinople by the members of the Fourth Crusade in 1204. The subsequent dismemberment of the Byzantine Empire weakened Christendom in the Near East and created an animousity between Catholics and Orthodox which has lasted into the 20th century. Below are excerpts of sources dealing with the crusaders siezure and looting of the largest city in Christendom.
Below is a description from Robert of Clari of the sermons given by the Latin bishops before the final attack on Constantinople, in which they justified attacking other Christians.
LXXII. When the pilgrims saw this, they were very angry and grieved much; they went back from the other side of the harbor to their lodgings. When the barons had returned and had gotten ashore, they assembled and were much amazed, and said that it was on account of their sins that they did not succeed in anything and could not capture the city. Meanwhile the bishops and the clergy in the army debated and decided that the war was a righteous one, and that they certainly ought to attack the Greeks. For formerly the inhabitants of the city had been obedient to the law of Rome and now they were disobedient, since they said that the law of Rome was of no account, and called all who believed in it Ad dogs." And the bishops said that for this reason one ought certainly to attack them, and that it was not a sin, but an act of great charity.
LXXIII. Then it was announced to all the host that all the Venetians and every one else should go and hear the sermons on Sunday morning; and they did so. Then the bishops preached to the army, the bishop of Soissons, the bishop of Troyes, the bishop of Havestaist  master Jean Faicette  and the abbot of Loos, and they showed to the pilgrims that the war was a righteous one; for the Greeks were traitors and murderers, and also disloyal, since they had murdered their rightful lord, and were worse than Jews. Moreover, the bishops said that, by the authority of God and in the name of the pope, they would absolve all who attacked the Greeks. Then the bishops commanded the pilgrims to confess their sins and receive the communion devoutly; and said that they ought not to hesitate to attack the Greeks, for the latter were enemies of God. They also commanded that all the evil women should be sought out and sent away from the army to a distant place. This was done; the evil women were all put on a vessel and were sent very far away from the army.
Below is a description by Villhardouin of the capture of the city.
Agreement between the Franks and the Venetians before Attacking Constantinople. Now let us leave speaking of those who avoided the host and speak of those before Constantinople. Well had these prepared all their engines, and mounted their petraries, and mangonels on the ships and on the transports, and got all such engines of war as are needful for the taking of and raised ladders from the yards and masts of the vessels so high that they were a marvel to behold.
And when the Greeks saw this, they began, on their side, to strengthen the defences of the city which was enclosed by high walls and high towers. Nor was any tower so high that they did not raise therein two or three stages of wood to heighten it still more. Never was city so well fortified. Thus did the Greeks and the Franks bestir themselves on the one side and the other during the greater part of Lent.
Then those of the host spoke together, and took counsel what they should do. Much was advanced this way and that, but in the end, they devised that if God granted them entry into the city by force, all the booty taken was to be brought together, and fittingly distributed; and further, if the city fell into their power, six men should be taken from among the Franks, and six from among the Venetians, and these twelve should swear, on holy relics, to elect as emperor the man who, as they deemed, would rule with most profit to the land. And whosoever was thus elected emperor, would have one quarter of whatever was captured, whether within the city or without, and moreover would possess the palace of Bucoleon and that of Blachernæ; and the remaining three parts would be divided into two, and one of the halves awarded to the Venetians and the other to those of the host.
And there should be taken twelve of the wisest and most experienced men among the host of the pilgrims, and twelve among the Venetians, and those twentyfour would divide fiefs and honours, and appoint the service to be done therefor to the emperor.
This covenant was made sure and sworn to on the one side and the other by the Franks and the Venetians; with provision that at the end of March, a year thence, any who so desired might depart hence and go the* way, but that those who remained in the land would be held to the service of the emperor in such manner as might be ordained. Thus was the covenant devised and made sure; and such as should not observe it were excommunicated by the clergy.
Attack of the Crusaders Repulsed--They Make Ready for Another Assault. The fleet was very well prepared and armed, and provisions were got together for the pilgrims. On the Thursday after midLent (8th April 1204), all entered into the vessels, and put their horses into the transports. Each division had its own ships, and all were ranged side by side; and the ships were separated from the galleys and transports. A marvellous sight it was to see; and well does this book bear witness that the attack, as it had been devised, extended over full half a French league.
On the Friday morning the ships and the galleys and the other vessels drew near to the city in due order, and then began an assault most fell and fierce. In many places the pilgrims landed and went up to the walls, and in many places the scaling ladders on the ships approached so close that those on the towers and on the walls and those on the ladders crossed lances, hand to hand. Thus lasted the assault, in more than a hundred places, very fierce, and very dour, and very proud, till near upon the hour of nones.
But, for our sins, the pilgrims were repulsed in that assault, and those who had landed from the galleys and transports were driven back into them by main force. And you must know that on that day those of the host lost more than the Greeks, and much were the Greeks rejoiced thereat And some there were who drew back from the assault, with the ships in which they were. And some remained with their ships at anchor so near to the city that from either side they shot at one another with petraries and mangonels.
Then, at vespers time, those of the host and the Doge of Venice called together a parliament, and assembled in a church on the other side of the straits-on the side where they had been quartered. There were many opinions given and discussed; and much were those of the host moved for the mischief that had that day befallen them. And many advised that they should attack the city on another side- the side where it was not so well fortified. But the Venetians, who had fuller knowledge of the sea, said that if they went to that other side, the current would carry them down the straits, and that they would be unable to stop their ships And you must know that there were those who would have been well pleased if the current had borne them down the straits, or the wind, they cared not whither, so long as they left that land behind, and went on their way. Nor is this to be wondered at, for they were in sore peril.
Enough was there spoken, this way and in that; but the conclusion of their deliberation was this: that they would repair and refit on the following day, which was Saturday, and during the whole of Sunday, and that on the Monday they would return to the assault; and they devised further that the ships that carried the scaling ladders should be bound together, two and two, so that two ships should be in case to attack one tower; for they had perceived that day how only one ship had attacked each tower, and that this had been too heavy a task for the ship, seeing that those in the tower were more in number than those on the ladder. For this reason was it well seen that two ships would attack each tower with greater effect than one. As had been settled, so was it done, and they waited thus during the Saturday and Sunday.
The Crusaders Take Part of the City. Before the assault the Emperor Mourzuphles had come to encamp, with all his power, in an open space, and had there pitched his scarlet tents. Thus matters remained till the Monday morning, when those on the ships, transports, and galleys were all armed. And those of the city stood in much less fear of them than they did at the beginning, and were in such good spirits that on the walls and towers you could see nothing but people. Then began an assault proud and marvellous, and every ship went straight before it to the attack. The noise of the battle was so great that it seemed to rend the earth.
Thus did the assault last for a long while, till our Lord raised a wind called Boreas which drove the ships and vessels further up on to the shore. And two ships that were bound together, of which the one was called the Pilgrim and the other the Paradise, approached so near to a tower, the one on the one side and the other on the other-so as God and the wind drove them-that the ladder of the Pilgrim joined on to the tower. Immediately a Venetian, and a knight of France, whose name was Andrew of Urboise, entered into the tower, and other people began to enter after them, and those in the tower were discomfited and fled.
When the knights see this, who are in the transports, they land, and raise their ladders against the wall, and scale the top of the wall by main force, and so take four of the towers. And all begin to leap out of the ships and transports and galleys, helterskelter, each as best he can; and they break in some three of the gates and enter in; and they draw the horses out of the transports; and the knights mount and ride straight to the quarters of the Emperor Mourzuphles. He had his battalions arrayed before his tents, and when his men see the mounted knights coming, they lose heart and fly and so goes the emperor flying through the streets to the castle of Bucoleon.
Then might you have seen the Greeks beaten down; and horses and palfreys captured, and mules, and other booty of killed and wounded there was neither end nor measure A great part of the Greek lords had fled towards the gate of Blachernæ. And vespers-time had already past, and those of the host were weary of the battle and of the slaying. And they began to assemble in a great open space that was in Constantinople, and decided that they would take up their quarters near the wall and towers they had captured. Never had they though that in a whole month they should be able to take the city, with its great church, and great palaces, and the people that were in It.
* * * * * * * * * * * * * * * * ** * *
During that night, towards the quarters of Boniface, Marquis of Montferrat, certain people, whose names are unknown to me, being in fear lest the Greeks should attack them, set fire to the buildings between themselves and the Greeks. And the city began to take fire, and to burn very direfully; and it burned all that night and all the next day, till vesperstime. And this was the third fire there had been in Constantinople since the Franks arrived in the land; and more houses had been burned in the city than there are houses in any three of the greatest cities in the kingdom of France.
That night passed and the next day came, which was a Tuesday morning (13th April 1204); and all armed themselves throughout the host, both knights and sergeants, and each repaired to his post. Then they issued from their quarters, and thought to find a sorer battle than the day before, for no word had come to them that the emperor had fled during the night. But they found none to oppose them.
The Crusaders Occupy the City. The Marquis Boniface of Montferrat rode all along the shore to the palace of Bucoleon, and when he arrived there it surrendered, on condition that the lives of all therein should be spared. At Bucoleon were found the larger number of the great ladies who had fled to the castle, for there were found the sister of the King of France, who had been empress, and the sister of the King of Hungary, who had also been empress, and other ladies very many. Of the treasure that was found in that palace I cannot well speak, for there was so much that it was beyond end or counting.
At the same time that this palace was surrendered to the Marquis Boniface of Montferrat, did the palace of Blachernæ surrender to Henry, the brother of Count Baldwin of Flanders, on condition that no hurt should be done to the bodies of those who were therein. There too was found much treasure, not less than in the palace of Bucoleon. Each garrisoned with his own people the castle that had been surrendered to him, and set a guard over the treasure. And the other people, spread abroad throughout the city, also gained much booty. The booty gained was so great that none could tell you the end of it: gold and silver, and vessels and precious stones, and samite, and cloth of silk, and robes vair and grey, and ermine, and every choicest thing found upon the earth. And well does Geoffrey of Villehardouin, the Marshal of Champagne, bear witness, that never, since the world was created, had so much booty been won in any city. .
Every one took quarters where he pleased, and of lodgings there was no stint. So the host of the pilgrims and of the Venetians found quarters, and greatly did they rejoice and give thanks because of the victory God had vouchsafed to them-for those who before had been poor were now m wealth and luxury. Thus they celebrated Palm Sunday and the Easter Day following (25th April I204) in the joy and honour that God had bestowed upon them. And well might they praise our Lord, since in all the host there were no more than twenty thousand armed men, one with another, and with the help of God they had conquered four hundred thousand men, or more, and in the strongest city in all the world-yea, a great city-and very well fortified.
Division of the Spoils. Then was it proclaimed throughout the host by the Marquis Boniface of Montferrat, who was lord of the host, and by the barons, and by the Doge of Venice, that all the booty should be collected and brought together, as had been covenanted under oath and pain of excommunication. Three churches were appointed for the receiving of the spoils, and guards were set to have them in charge, both Franks and Venetians, the most upright that could be found.
Then each began to bring in such booty as he had taken, and to collect it together. And some brought in loyally, and some in evil sort, because covetousness, which is the root of all evil, let and hindered them. So from that time forth the covetous began to keep things back, and our Lord began to love them less. Ah God! how loyally they had borne themselves up to now! And well had the Lord God shown them that in all things He was ready to honour and exalt them above all people. But full oft do the good suffer for the sins of the wicked.
The spoils and booty were collected together, and you must know that all was not brought into the common stock, for not a few kept things back, maugre the excommunication of the Pope. That which was brought to the churches was collected together and divided, in equal parts, between the Franks and the Venetians, according to the sworn covenant. And you must know further that the pilgrims, after the division had been made, paid out of their share fifty thousand marks of silver to the Venetians, and then divided at least one hundred thousand marks between themselves, among their own people. And shall I tell you in what wise ? Two sergeants on foot counted as one mounted, and two sergeants mounted as one knight. And you must know that no man received more, either on account of his rank or because of his deeds, than that which had been so settled and ordered- save in so far as he may have stolen it.
And as to theft, and those who were convicted thereof, you must know that stern justice was meted out to such as were found guilty, and not a few were hung. The Count of St. Paul hung one of his knights, who had kept back certain spoils, with his shield to his neck; but many there were, both great and small, who kept back part of the spoils, and it was never known. Well may you be assured that the spoil was very great, for if it had not been for what was stolen and for the part given to the Venetians, there would have been at least four hundred thousand marks of silver, and at least ten thousand horses-one with another. Thus were divided the spoils of Constantinople, as you have heard.
Below is a Byzantine account of the sack by Nicetas Chroniates.
3. . . How shall I begin to tell of the deeds wrought by these nefarious men ! Alas, the images, which ought to have been adored, were trodden under foot ! Alas, the relics of the holy martyrs were thrown into unclean places ! Then was seen what one shudders to hear, namely, the divine body and blood of Christ was spilled upon the ground or thrown about. They snatched the precious reliquaries, thrust into their bosoms the ornaments which these contained, and used the broken remnants for pans and drinking cups,-precursors of Antichrist, authors and heralds of his nefarious deeds which we momentarily expect. Manifestly, indeed, by that race then, just as formerly, Christ was robbed and insulted and His garments were divided by lot; only one thing was lacking, that His side, pierced by a spear, should pour rivers of divine blood on the ground.
Nor can the violation of the Great Church be listened to with equanimity. For the sacred altar, formed of all kinds of precious materials and admired by the whole world, was broken into bits and distributed among the soldiers, as was all the other sacred wealth of so great and infinite splendor.
When the sacred vases and utensils of unsurpassable art and grace and rare material, and the fine silver, wrought with gold, which encircled the screen of the tribunal and the ambo, of admirable workmanship, and the door and many other ornaments, were to be borne away as booty, mules and saddled horses were led to the very sanctuary of the temple. Some of these which were unable to keep their footing on the splendid and slippery pavement, were stabbed when they fell, so that the sacred pavement was polluted with blood and filth.
4. Nay more, a certain harlot, a sharer in their guilt, a minister of the furies, a servant of the demons, a worker of incantations and poisonings, insulting Christ, sat in the patriarch's seat, singing an obscene song and dancing frequently. B'or, indeed, were these crimes committed and others left undone, on the ground that these were of lesser guilt, the others of greater. But with one consent all the most heinous sins and crimes were committed by all with equal zeal. Could those, who showed so great madness against God Himself, have spared the honorable matrons and maidens or the virgins consecrated to God? Nothing was more difficult and laborious than to soften by prayers, to render benevolent, these wrathful barbarians, vomiting forth bile at every unpleasing word, so that nothing failed to inflame their fury. Whoever attempted it was derided as insane and a man of intemperate language. Often they drew their daggers against any one who opposed them at all or hindered their demands.
No one was without a share in the grief. In the alleys, in the streets, in the temples, complaints, weeping, lamentations, grief, the groaning of men, the shrieks of women, wounds, rape, captivity, the separation of those most closely united. Nobles wandered about ignominiously, those of venerable age in tears, the rich in poverty. Thus it was in the streets, on the corners, in the temple, in the dens, for no place remained unassailed or defended the suppliants. All places everywhere were filled full of all kinds of crime. Oh, immortal God, how great the afflictions of the men, how great the distress !
While most objects of ancient and Byzantine art were destroyed, the relics of saints were eagerly sought out. Below is a description by Gunther of the theft of relics by Abbot Martin.
While the victors were rapidly plundering the conquered city, which was theirs by right of conquest, the abbot Martin began to cogitate about his own share of the booty, and lest he alone should remain emptyhanded, while all the others became rich, he resolved to seize upon plunder with his own sacred hands. But, since he thought it not meet to handle any booty of worldly things with those sacred hands, he began to plan how he might secure some portion of the relics of the saints, of which he knew there was a great quantity in the city.
Accordingly, having a presentiment of some great result, he took with him one of his two chaplains and went to a church which was held in great reverence because in it the mother[14 ] of the most famous emperor Manuel had a noble grave, which seemed of importance to the Greeks, but ours held for naught. There a very great amount of money brought in from all the surrounding country was stored, and also precious relics which the vain hope of security had caused them to bring in from the neighboring churches and monasteries. Those whom the Greeks had driven out, had told us of this before the capture of the city. When many pilgrims broke into this church and some were eagerly engaged in stealing gold and silver, others precious stones,
Martin, thinking it unbecoming to commit sacrilege except in a holy cause, sought a more retired spot where the very sanctity of the place seemed to promise that what he desired might be found. There he found an aged man of agreeable countenance, having a long and hoary beard, a priest, but very unlike our priests in his dress. Thinking him a layman, the abbot, though inwardly calm, threatened him with a very ferocious voice, saying: a Come, perfidious old man, show me the most powerful relics you have, or you shall die immediately." The latter, tenified by the sound rather than the words, since he heard but did not understand what was said, and knowing that Martin could not speak Greek, began in the Romana Zinpa, of which he knew a little, to entreat Martin and by soft words to turn away the latter's wrath, which in truth did not exist. In reply, the abbot succeeded in getting out a few words of the same language, sufficient to make the old man understand what he wanted. The latter, observing Martin's face and dress, and thinking it more tolerable that a religious man should handle the sacred relics w,th fear and reverence, than that worldly men should, perchance, pollute them with their worldly hands, opened a chest bound with iron and showed the desired treasure, which was more grateful and pleasing to Martin than all the royal wealth of Greece. The abbot hastily and eagerly thrust in both hands and working quickly, filled with the fruits of the sacrilege both his own and his chaplain's bosom. He wisely concealed what seemed the most valuable and departed without opposition.
Moreover what and how worthy of veneration those relics which the holy robber appropriated were, is told more fully at the end of this work.l When he was hastening to his vessel, so stuffed full, if I may use the expression, those who knew and loved him, saw him from their ships as they were themselves hastening to the booty, and inquired joyfully whether he had stolen anything, or with what he was so loaded down as he walked. With a joyful countenance, as always, and with pleasant words he said: As We have done well." To which they replied: a Thanks be to God."
While Pope Innocent III excommunicated the Crusaders after their sack of the catholic city of Zara (Zadar in Croatia), he later lifted the bull of excommunication and justified the capture of Constantinople in the letter below.
To all the clergy and people in the Christian army at Constantinople.
If the Lord had granted the desires of His humble servants sooner, and had transferred, as He has now done, the empire of Constantinople from the Greeks to the Latins before the fall of the Holy Land, perhaps Christianity would not be weeping today over the desolation of the land of Jerusalem. Since, therefore, through the wonderful transference of this empire God has deigned to open to you a way to recover that land, and the detention of this may lead to the restoration of that, we advise and exhort you all, and we enjoin upon you for the remission of your sins, to remain for a year in Romania, in order to strengthen the empire in its devotion to the Apostolic See and to us, and in order to retain it in the power of the Latins; and to give wise advice and efficient aid to Baldwin, our most beloved son in Christ, the illustrious emperor of Constantinople; unless, perchance, your presence in the Holy Land should be necessary before that time, in which case you ought to hasten to guard it before the year elapses. Dated, . . . . 
 "The Fourth Crusade" Translations and Reprints from the Original Sources in European History, Dana Carlton Munro, ed. and tr., vol. III, no. 1 (University of Pennsylvania, 1907), pp. 13-14. Original found in Robert de Clari, ch. lxxiilxxiii, in Hopf: Chroniques, pp. 5758. Old French.
 That the attack was repulsed.
 Apr. II, 1204.  Halberstadt.
 De Noyon, chancellor of Baldwin of Flanders.
 Villehardouin and De Joinville, Memoirs of the Crusades, Frank Marzials, tr. and ed. (London: Everyman's Library, 1908), pp. 58-66.
 This passage is obscure in the original.
 Agnes, sister of Philip Augustus, married successively to Alexius II to Andronicus, and to Theodore Branas.
 Margaret, sister of Emeric, King of Hungary, married to the Emperor Isaac, and afterwards to the Marquis of Monferrat.
 "The Fourth Crusade" Translations, pp. 15-16. Orginally found in Nicetas: Atexii Ducae Imperium, ch. iiiiv, in Recueil des historiens des Crusades, hist. grec., I, 397. Greek.  Hagia Sophia.
 "The Fourth Crusade" Translations, pp. 16-18. Originally found in Gunther: Historia Constantinopolitana, ch. xix, in Riant: Exmviae, Vol 1, 104 ff. Latin.
 The church of Pantokrator.
 Irene, died 1124.
 Manuel I Comnenos
 "The Fourth Crusade" Translations, p. 20 Originally in Epistolae, Bk. viii, No. 63, in Tessier: Diversion, etc., pp. 2356. Latin.
 Potthast: Regesta went. Rern., No. 2507, gives date as possibly May 20, 1205.