In the mid-17th century, New France was seriously threatened by the Iroquois. In 1665, to repel the Aboriginal peoples and restore the settlers' confidence, Louis XIV sent over the Carignan-Salières Regiment. They built a number of forts on the Richelieu River in order to prevent the Iroquois from using the waterway to attack the settlements of the St. Lawrence Valley. One of the first forts was Fort Chambly, erected in 1665 by Jacques de Chambly, captain of the Carignan-Salières Regiment. It was situated below the rapids, where the Richelieu River forms a basin. The fort was reinforced in 1710-1711. Because of its position, this uniform, fortified stone structure of equal angles blocked access to the navigable part of the Richelieu in the direction of the St. Lawrence, and stood between the enemy and Montréal. In 1665, the Carignan-Salières Regiment also built Fort Richelieu at the mouth of the Richelieu River. It was erected on the site of an earlier fort built by Charles Huault de Montmagny, first Governor and Lieutenant-Governor of New France, and destroyed by the Iroquois in 1647.

Richelieu River Forts
Plan du fort Richelieu [Plan of Fort Richelieu], ca. 1665