OK, now that a little misunderstanding has been cleared up, I can post Pt 1 of this. The question of the effects of this POD on the Fifth Crusade is actually more important than I originally thought, since in OTL the movement of forces to Egypt depended on an alliance with the Seljuks. No Seljuks no alliance. The Empire has less than zero interest in fighting the Ayyubids this soon after a devastating war which results in the army being seriously overstretched to defend the gains they already have. So I've had the Armenian Kingdom of Cilicia step up. Without the Seljuks pushing in on them, the Armenians are a lot more secure, which could lead to a more aggressive foreign policy. I'm presuming basically positive relations with the Empire -- most likely the King formally acknowledges the notional supremacy of the Emperor.
"The Doge is dead. The Greek Prince will not last the night. It is disaster."
One disaster after another. The Venetians were sure to leave now, leaving the Crusade stranded without a fleet. The prince they had been promised would be welcomed by grateful throngs had been rejected by his alleged subjects and was burning up with fever, shaking like a leaf. And the common soldiers were listening to the crazed hermit that had been preaching that repentance and submission to God's Vice Regent on Earth was the only cure for the disease running through the camp. Boniface of Montferrat had succumbed early, as had Baldwin of Flanders, and with Enrique Dandolo dead now, the army could not be held together. It was up to him, Louis of Blois, to find a solution. He looked around the council of second-rank leaders who had replaced the great men who had guided the Crusade until now. He marked the sign of fever in the eyes of a few, and defeat in the rest.
There was a heavy silence. "We have few choices now. The Venetian ships will leave soon." A sharp nod from the Venetian captain who was the senior leader of that city's fleet. "This pestilence is destroying us, and the soldiers believe God has forsaken them for our sins. At this point I am ready to agree." No one argued. "I am ready to send for the hermit. Perhaps he can keep the soldiers from mutiny while we extricate ourselves from this disaster. In the morning, I will send heralds to the Greeks to speak to them of our return to our homes. We have failed."
The meeting was broken up by shouting outside. Those who heard it had no doubt of what it meant. The men had discovered the Doge was dead.
In the morning, Louis finally admitted to himself that he had lost control of the situation entirely. Not only had the men discovered the Doge was dead, but some treacherous servant had let that damnable hermit into his private tent. Into his private papers. Within an hour or less, the entire army knew they had been excommunicated for the attacks on Zara and Constantinople. Only quick thought, the claim that Dandolo had lied to him as well, and loyal men with drawn swords prevented a mob from murdering the members of the army council. Order was restored with daylight, but only the admission of Petros to the ranks of the council had permitted this. The Greek prince Alexius had indeed died in the confusion. Petros promised the men, on behalf of the council, that they would have a chance to earn pardon for all misdeeds they had been led into by treacherous leaders. With the council, he was blunt, almost demanding. Unfortunately, Louis saw no alternative that would not have the army rioting out of control again. At least everything could be blamed on the dead leaders. Peter insisted that the fleet begin ferrying the army across the strait again, and men were leaving behind their plunder, derisively referred to as the 'wages of sin' by the monk. On the other shore, a new camp was being prepared as a base for the new direction of campaign.
Early June 1203 – Disease sweeps the assembled Crusader army, killing Enrique Dandolo, Boniface, and Alexius IV, throwing the Army into confusion. A hermit, Peter, appears, preaching that this is retribution for attacking fellow Christians. The letters sent to Dandolo from the Pope fulminating against his attack on Zara are published in the army. A council of nobles is set up to command the Army with Peter’s advice and with the mandate to swiftly remove the Crusaders from Constantinople’s environs and strike against “the infidels” as swiftly as possible. Nearly simultaneously, Theodore Lascaris, with the support of the Varangians and other soldiers in the City, moves to arrest and blind Alexius III, tonsure him as a monk, and smuggles him out to the Crimea in the dead of night. Isaac II also takes monastic vows and is removed to a small rock in the Aegean.
July 1203 – The disease abates as the Crusaders are shuttled over the straits of Mamara. Peter’s advice is a mixture of the immensely practical, about latrine placement and sleeping arrangements, and spiritual.
August 1203 – Shadowed and supported by Cuman and Pecheneg mercenaries in Roman pay, the Crusaders meet the Seljuk army hurriedly gathered to meet them. Spurred on by renewed religious fervor and with some unexpectedly practical advice from Peter, the Crusaders are victorious in a series of pitched battles. In a bid to maintain the favor of God, the Crusaders return conquered cities to Roman rule.
"My Brothers!" the Emperor began. Four years ago that would be unthinkable, but four years of constant fighting alongside the Franks had rendered them not only less alien, but brothers indeed. "We have won great victories. We have swept the Turk from lands which have not been ruled by Christians in a century. We have done this, not seperately as Roman and Frank, but as fellow soldiers of Christ, fellow Christians, fellow warriors. We have shed blood together, suffered greatly together, and at last have come to stand together against the Saracen as invincible through the power of the life-giving Cross and by the blessings of the Saints. Now we have overthrown a great power of the infidels, and it is fitting that as our brothers in arms, we should reward your steadfast faith and valor. So We lay before you three choices. Know that however each of you chooses, you shall ever after be honored as a citizen of Our Empire, to be treated as such should you ever return, for your blood shed on Roman soil alongside Roman blood has made you more worthy to be counted as such than many who enjoy the pleasures of the City without striving for its defense."
"The first choice before you is to become one of us. We will have need of strong warriors to defend Our lands, and strong men to raise up sons to defend our lands. We can think of nothing better than for you to live among us. Each man who chooses this path shall be given lands commensurate with his rank, in order to maintain himself properly.
"On the other hand, some of you may wish to return to your homeland. We pledge that none shall leave without gold commensurate to the great services rendered, and We shall pay passage and hire the ships to return you. Or, should you wish it, the Frankish Kingdom of Jerusalem has need of fighting men, and We shall hire ships to take you there and give you gold to sustain yourselves for a time."
1207 – Last vestiges of the Sultanate of Rum is overrun by Crusaders, now with Roman regulars fighting alongside the Crusader army. The Emperor Theodore Lascaris offers the Crusaders three choices – to swear fealty and receive grants of Roman land, transportation back to the West with gifts of gold, taken from the Imperial share of the plunder of the Turks, as their reward for pious and valiant deeds, or transportation to the Kingdom of Jerusalem to continue to serve God there. Roughly half of the nobles and two thirds of the lesser warriors choose to stay in the Empire. Peter retires to a monastery in Thrace, claiming his mandate from God was complete.
1207-1220: A period of largely peaceful reorganization of the Empire. A short, sharp war absorbed the Mengucek Beylik. Administration of Anatolia was organized from the ground up, and much of the recovered territory had to be repopulated. Some numbers of Turks were accepted, most of whom converted to Christianity. Most importantly, the Romans turned westward, creating new and more equitable relations with the Italian city states of Genoa and Venice. Western fashions and culture become the rage, as the Roman Empire seems to celebrate a new awakening.
1216-1217: Fifth Crusade attracts armies from across Europe to Antioch
1218: Oliver of Cologne arrives in Syria with additional forces for the Crusade. He attempts to negotiate an alliance with the Empire in order to cooperate in defeating the Ayyubids, but the Empire refuses to start another war. Oliver secures an alliance with King Levon I of the Armenian Kingdom of Cilicia. The Crusaders take ship to Damietta.
June 1218 – November 1219: Siege of Damietta. Crusaders under Papal Legate Pelagius of Albano begin bickering with the Kingdom of Jerusalem over possession.
1218-1220: Mongols defeat Khwarezm Empire and raid through Armenia and Georgia, reaching the Crimea before retreating. Georgians are defeated but not occupied.
1221: Peaceful succession of Ioannes III Ducas Vatatzes, son-in-law of Theodore Lascaris. He reforms tax collection, making it both more equitable and more efficient, emphasizes economy, and improves the professionalism of the native Roman forces. He also returns the hyperpyron to a proper standard of weight and purity.
Early 1221: Armenian defeat results in truce between Cilicia and Ayyubids on terms of status quo ante bellum.
July 1221: Crusaders march from Damietta to Cairo, but are defeated, surrounded, and forced to surrender Damietta in return for release of the Crusaders and an eight year truce.
1224: Ioannes Vatatzes begins a major naval building program.