The Lachine massacre, part of the Beaver Wars, occurred when 1,500 Mohawk warriors launched a surprise attack against the small (375 inhabitants) settlement of Lachine, New France, at the upper end of Montreal Island on the morning of August 5, 1689. The attack was precipitated by growing Iroquois frustration with the increased French incursions into their territory, ongoing concern about French Marquis de Denonville's attack of 1687, and was encouraged by the settlers of New England as a way to leverage power against New France during King William's War.