The situation of the colony at that time was most critical, owing to Frontenac's departure, the weakness of Governor de la Barre, and the woeful error of the French government in sending some Iroquois chiefs captured at Cataracoui (Kingston) to be galley slaves in France.

A valiant and experienced soldier, he aided Frontenac in saving New France from the Iroquois and in raising the prestige of the French flag.

François de Callières, the eldest son, was elected to the French Academy in 1689 and also served with distinction in Louis XIV's diplomatic corps.

In 1701, thanks to his ability to imitate the royal handwriting and to his mastery of the French language, succeeded Toussaint Rose as the secretary "who held the pen."

His duties, designed to save the monarch time and fatigue, consisted of writing in a hand and style similar to those of the king letters and memoirs to dignitaries and foreign heads of state and of signing them with the royal name.