 In France, he resumed his studies with the thought of joining the French cavalry, but following the Treaty of Paris (1763) and the consequent loss of his father's land in America, he returned to Quebec and was commissioned as a military surveyor in 1768.From 1770, his father had incurred many debts, so with the financial help of his father's friend Charles-François Tarieu de La Naudière, he kept the seigneuries of Lotbiniere, Vaudreuil, Rigaud and Rigaud de Vaudreuil (which he sold in 1772 to his uncle) in the family by purchasing them from his father.Although only in his early twenties, through his immense properties, prestigious name and family connections he was now one of the most influential Canadian seigneurs.