The violence of 1182 did not arrive without warning. From the late eleventh century, merchants from Venice, Genoa, Pisa, and Amalfi had established a growing commercial presence in Constantinople, backed by trading concessions that Byzantine emperors had granted in exchange for naval support. Emperor Alexios I Komnenos first opened the gates to Venetian traders on generous terms. Subsequent emperors extended similar privileges to the other Italian cities, each community eventually winning its own quarter in the northern part of the capital, toward the Golden Horn. By 1180, an estimated 60,000 Latin residents lived in Constantinople — a substantial minority in a city of perhaps 400,000 people. They dominated maritime trade and much of the financial sector. For ordinary Byzantine merchants, their virtual stranglehold was a source of real economic injury. For the wider population, it bred resentment of the kind that political crisis could ignite.

Emperor Manuel I Komnenos died in 1180, leaving an eleven-year-old heir, Alexios II, under the regency of his mother, Empress Maria of Antioch — herself of Latin origin — and her favorite, the *protosebastos* Alexios Komnenos. The regency was unpopular; the influence of the empress and her Latin-sympathizing court was resented. Into this tension stepped Andronikos Komnenos, a charismatic imperial cousin and rival who marched on Constantinople in 1182, appealing to anti-Latin sentiment among the population. The historian's record on Andronikos is complicated: he does not appear to have harbored personal hatred of the Latins, but he made use of the population's anger and, crucially, allowed the violence to proceed once it began. He had spread the accusation that the empress and the *protosebastos* had promised the Latins the opportunity to plunder the city — a claim that accelerated the fury already building in the streets.

What happened in April 1182 was a massacre. Crowds moved through the Latin quarters of Constantinople — the Genoese district, the Venetian quarter, the Pisan settlement — attacking residents with weapons and fire. The victims included merchants and their families, craftsmen, monks, and priests. Hospital patients were killed in their beds. Latin churches were attacked. Those who could flee to ships in the harbor sometimes escaped; many did not, and survivors were in numerous cases sold into slavery. The Empress Maria was placed under house arrest during the violence; she was later executed. The scale of the killing is not precisely recorded in the sources, but it was large enough to register as a defining event in Byzantine-Western relations for generations afterward — a rupture felt immediately and never fully healed.

The aftermath was swift and consequential. The Western states were horrified. Regular trade resumed before long, because economic necessity drove both sides back to the table, but the underlying wound did not close. William II of Sicily launched an expedition in 1185 that sacked Thessalonica, Byzantium's second city. The German emperors Frederick Barbarossa and Henry VI both made threats against Constantinople in the following years. Pope Innocent III condemned the massacre. And in 1204, the Fourth Crusade — ostensibly bound for the Holy Land — turned instead toward Constantinople. The Crusaders sacked the city, installed a Latin emperor, and ended the Byzantine world's political continuity for over fifty years. The events of 1182 were not the only cause of 1204, but they were among its preconditions: they confirmed to the Latin West that Byzantium was an enemy, and they stored up a grievance that some in the Crusading movement were prepared to act upon.

The massacre of April 1182 has never achieved the notoriety of the Fourth Crusade's sack of Constantinople, which came twenty-two years later. Historian Warren Carroll noted this disparity plainly: those who record the sack of Constantinople by the Crusaders rarely mention what happened to the Latins in 1182. Both events involved mass killing and profound violation. Both deserve to be remembered with honesty. For the thousands of Latin residents who died in those April streets — the merchants and their children, the monks in their churches, the patients in their hospital beds — the category that killed them was not their fault to bear. They were the casualties of forces far larger than themselves: commercial rivalry, political opportunism, and the slow poisoning of two Christian traditions that had once shared a faith.