Dramatic events soon forced Canadians to put the new military tactics, which had just proved so effective at a distance with d'Iberville's Hudson Bay exploits, into practice closer to home. Despite the defeat they had suffered two years earlier at the hands of Denonville, the Iroquois, encouraged by Americans from the colony of New York, began again in 1689 to harass French settlements. This was the context for the attack on Lachine, a small village upstream from Montreal, in August of that year. According to Frontenac, its inhabitants were massacred with "unparalleled and unprecedented horror." 
Passing into history as "the massacre of Lachine," this event acted as a catalyst for a formidable response.
In 1689, war broke out in Europe among several countries, including England and France. The Iroquois attack could be seen as the action of a people who had become a tool of the neighbouring English colonies to the south. Back in New France on his second mandate, Frontenac gathered his staff. From a strategic point of view, the time had come for a counterattack. The real enemies had to be dealt a blow in their homeland, he said, as quickly as possible, and in a way that would place them on the defensive.