The roots of the massacre stretched back decades into the tangled economics of beaver pelts. European settlers in the American Northeast had built a lucrative fur trade with Indigenous nations, and the Iroquois Confederacy -- particularly the Mohawk -- were central players. But French colonial ambitions kept pushing the boundaries. Jesuit missionaries pressed for cultural assimilation, demanding that Indigenous peoples abandon their traditions. French traders armed rival nations. And when the Iroquois raided western trading parties under French protection, the colonial government responded with devastating military force. In 1666, two French expeditions burned Mohawk villages and destroyed their winter corn supply. Twenty years later, the Marquis de Denonville invaded Seneca territory and obliterated an estimated 1,200,000 bushels of corn, crippling the Iroquois economy. The Mohawk did not forget. They could not afford to.

By 1689, the Iroquois were caught between two European powers using North America as a chessboard. England and France had declared war on each other, and despite the 1686 Treaty of Whitehall -- which promised that European conflicts would not disrupt colonial peace -- both sides enlisted Indigenous allies as proxies. English colonists in the Province of New York actively encouraged the Iroquois to strike New France's exposed settlements. The French, meanwhile, had left their frontier communities dangerously undefended. Farms and villages were scattered and isolated, connected by little more than the Saint Lawrence River. Lachine, perched at the upper end of Montreal Island, was the main departure point for westward-traveling fur traders -- a hub of French commercial power and an irresistible target.

The attack came under cover of darkness and rain. The Mohawk warriors traveled up the Saint Lawrence by boat, crossed Lake Saint-Louis, and fanned out across the south shore of the island. They surrounded the colonists' homes and waited in silence for the signal. When it came, the assault was swift and overwhelming. Homes were set ablaze. Colonists were dragged from their beds. The settlement's wooden structures offered little resistance to fire. Historian Charles W. Colby, working from Catholic parish registers, determined that 24 colonists were killed outright, though earlier accounts -- including Justin Winsor's 1884 estimate of more than 200 dead -- inflated the toll dramatically. Over 120 settlers were taken prisoner. Word of the attack reached a nearby garrison when a survivor stumbled in to raise the alarm. The French mobilized 200 soldiers under Daniel d'Auger de Subercase, along with 100 armed civilians from Forts Remy, Rolland, and de La Presentation, but the counterattack came too late to prevent the destruction.

Every written record of the Lachine massacre came from French pens. Survivors described 48 prisoners being tortured, burned, and cannibalized shortly after capture. Francois Vachon de Belmont, the fifth superior of the Sulpicians of Montreal, recorded harrowing testimony in his History of Canada. But historians have long cautioned that these accounts carry the biases of their authors. Canadian historian John A. Dickinson has argued that while the cruelty of the Iroquois was real, the threat was "neither as constant nor terrible as the contemporary sources represented." The Mohawk left behind English-supplied firearms during their retreat -- physical evidence that the attack was not solely an Indigenous initiative but part of a broader imperial proxy war. Iroquois accounts of the raid, preserved only through oral tradition, have not survived in written form. The story that endures is overwhelmingly one-sided.

The aftermath reshaped the politics of the continent. Louis de Buade de Frontenac took over as governor in October 1689 and immediately launched retaliatory raids against English settlements to the south, striking "in Canadien style" during the brutal winter months of 1690. The most infamous of these counter-raids was the Schenectady massacre, which mirrored Lachine in its surprise, its violence, and its escalation of a conflict that would drag on for years. Today, the borough of Lachine has grown into a residential neighborhood of southwest Montreal, its waterfront lined with parks and cycling paths along the Lachine Canal. A small plaque near the old settlement site marks the events of that August morning. The fur trade that fueled the bloodshed is long gone, but the story of Lachine endures as a reminder of how commerce, colonialism, and cultural collision once turned this quiet stretch of riverbank into a flashpoint of continental war.