After wintering in Guadeloupe, Tracy, Berthier and the soldiers that had accompanied them left the West Indies for the Gulf of St. Lawrence aboard the Brèse.

When Bishop François de Laval discovered that there were significant numbers of Huguenots within the ranks of the French soldiers, corrective measures were taken.

Since he was an officer who had been commissioned by the king, Berthier abjured in a private ceremony on October 7, 1665, conducted by Laval and witnessed by Tracy.

The fort, located in present-day Saint-Marc-sur-Richelieu, was one of several that Tracy ordered built astride the route that the Iroquois used to attack settlements on the St. Lawrence River.

[6] Later that year, Berthier and Chambly co-commanded the rear guard during Tracy's large-scale expedition against the Mohawk, one of the five Iroquois nations.

In the late summer of 1669 Bertier volunteered to return to New France as captain of a company of the Troupes de la Marine.

[7] Berthier commanded a company of Canadian militia during the Marquis de Denonville's expedition against the Seneca in 1789 that destroyed four of their villages.