A Desperate Prince in Exile

In mid-December 1202, the leaders of the Fourth Crusade gathered in the conquered city of Zara were met with an unexpected visitor—Alexios Angelos, a young Byzantine prince. Though only 20 years old, Alexios carried the weight of a stolen throne. His uncle had usurped the imperial crown of Byzantium, imprisoned him, and left him with no choice but to flee. After a daring escape, Alexios crossed the Alps to seek aid from his brother-in-law, Philip of Swabia, King of Germany. Armed with Philip’s endorsement, the exiled prince now stood before the Crusader lords, pleading for their help.

His proposal was bold: divert the Crusade to Constantinople, overthrow his usurping uncle, and restore him to the throne. In return, he offered staggering rewards—200,000 silver marks, funding for 10,000 soldiers to attack Egypt, 500 Byzantine knights to defend the Holy Land, and the submission of the Greek Orthodox Church to the Pope in Rome.

The Crusaders’ Dilemma

The Crusade’s leaders were stunned. For the French nobles, this was an unforeseen twist. Geoffrey of Villehardouin, the chronicler of the Crusade, recorded no prior discussions about such a plan. Yet one man was unsurprised: Boniface of Montferrat, the Crusade’s commander.

Montferrat had previously met with Philip of Swabia—where Alexios was staying—raising suspicions of secret negotiations. Now, he championed the prince’s cause, arguing that diverting to Constantinople would solve their financial woes, bolster their forces, and even achieve the long-sought unity of Christendom under Rome.

The Venetians, led by the pragmatic Doge Enrico Dandolo, saw opportunity. Venice had long clashed with Byzantium over trade, and a friendly emperor in Constantinople could secure their dominance in the eastern Mediterranean. Dandolo, a seasoned diplomat, cared little for religious zeal—his loyalty was to Venice first, Christianity second.

Division and Departure

The Crusaders fractured. Some, appalled at attacking fellow Christians, deserted. A group of 500 knights seized Venetian ships to sail for Egypt, only to founder without skilled sailors. Others attempted an overland march to Palestine but were driven back by Hungarian forces.

In the end, the majority agreed to Alexios’s terms. A formal contract was signed, binding the Crusade to his cause. Pope Innocent III, though furious at this deviation, held his tongue—unification of the churches under Rome was too tantalizing a prize to oppose outright.

The Siege of Constantinople

On April 6, 1203, the Crusader fleet set sail. By June, they reached Constantinople, its towering walls and golden domes dazzling the Westerners. Dandolo, the only leader with firsthand knowledge of the city, urged caution: a direct assault would be suicide. Instead, he proposed securing nearby islands for supplies before striking.

The French ignored him. On June 24, they launched their attack, beginning a grueling 10-month siege. Despite Byzantium’s legendary defenses, internal strife and Venetian naval ingenuity turned the tide. By April 1204, the city fell—but not before Alexios and his uncle were dead, murdered by a rival claimant.

The Birth of the Latin Empire

With Byzantium in chaos, the Crusaders carved out a new realm: the Latin Empire. A council of six French and six Venetian electors chose Baldwin of Flanders as emperor, while Venice claimed three-eighths of Byzantine territory, including key ports. The Greek Church was forcibly subjected to Rome, and Venetian merchants gained exclusive trading rights.

Yet the Latin Empire was fragile. The Crusaders, now rulers of a fractured state, faced revolts, financial strain, and the lingering shadow of Byzantium’s exiled nobility. Meanwhile, Venice reaped the benefits, securing its maritime empire at the expense of Christian unity.

Legacy of Betrayal

The Fourth Crusade’s diversion to Constantinople remains one of history’s great ironies. Intended to reclaim Jerusalem, it instead shattered the Byzantine Empire, weakened Christendom, and deepened the rift between East and West. For Venice, it was a triumph of realpolitik; for the Crusaders, a moral and strategic failure.

Even Pope Innocent III, who had dreamed of church unity, lamented the outcome. The Crusade’s legacy endures as a cautionary tale—of ambition, opportunism, and the unintended consequences of holy war.