The Society of Priests of Saint-Sulpice (French: Compagnie des Prêtres de Saint-Sulpice), abbreviated PSS, also known as the Sulpicians is a society of apostolic life of Pontifical Right for men, named after the Church of Saint-Sulpice, Paris, where it was founded. The members of the Society add the nominal letters PSS after their names to indicate membership in the Congregation. Typically, priests become members of the Society of the Priests of St. Sulpice only after ordination and some years of pastoral work. The purpose of the society is mainly the education of priests and ,to some extent parish work. As their main role is the education of those preparing to become priests, Sulpicians place great emphasis on the academic and spiritual formation of their own members, who commit themselves to undergo lifelong development in these areas. The Society is divided into three provinces, operating in various countries: the Province of France, Canada, and the United States

The Sulpicians played a major role in the founding of the Canadian city of Montreal, where they engaged in missionary activities, trained priests and constructed the Saint-Sulpice Seminary.

The Société Notre-Dame de Montréal, of which Jean-Jacques Olier was an active founder, was granted the land of Montreal from the Company of One Hundred Associates, which owned New France, with the aim of converting the indigenous population and providing schools and hospitals for both them and the colonists. The Jesuits served as missionaries for the small colony until 1657 when Jean-Jacques Olier sent four priests from the Saint-Sulpice seminary in Paris to form the first parish. In 1663, France decided to substitute direct royal administration over New France for that hitherto exercised by the Company of One Hundred Associates, and in the same year, the Société Notre-Dame de Montréal ceded its possessions to the Seminaire de Saint-Sulpice. Just as in Paris, the Montreal Sulpicians had important civil responsibilities. Most notably, they acted as seigneurs for the island of Montreal.

The Sulpicians served as missionaries, judges, explorers, schoolteachers, social workers, supervisors of convents, almsmen, canal builders, urban planners, colonization agents, and entrepreneurs. Despite their large role in society and their influence in shaping early Montreal, each night they would all return to the Saint-Sulpice Seminary. The administration of the Séminaire de Montreal was modeled on that of the Séminaire de Paris, in which the company was run by the superior, the four-man Consulting Council, and the Assembly of Twelve Assistants. According to the rules of the seminary in 1764, the superior, during his five-year renewable term, was to act like a father and was to be respected. The seminary kept careful records of all employees, including birthdays, place of birth, marital status, and salary. Female employees posed a particular problem since although a cheap source of labour, their presence in a male religious community was problematic. The superior of the Séminaire de Montréal was inherently also the Island of Montreal's seigneur. In the case of M. Vachon de Belmont, who was responsible for the mission of La Montagne, sixth superior of the Montreal Sulpicians, the master designer of the fort and Sulpicians' residential château, and who was independently wealthy, was very well educated and had trained as draughtsman and architect, M. Belmont had a more than passing interest in military strategy and architecture. M. Belmont's military strategy stamp is also evident in the implementation of the Sault-au-Récollet's fr: Fort Lorette and the seigneurie Lac-de-Deux-Montagnes' fort.

In 1668, several Sulpicians went to evangelize the Haudenosaunee in the Bay of Quinte (Belleville), north of Lake Ontario, the Mi'kmaq in Acadia, the Haudenosaunee on the present site of Ogdensburg in the State of New York and, finally, the Algonquins in Abitibi and Témiscamingue. Dollier de Casson and Brehan de Gallinée explored the region of the Great Lakes (1669), of which they made a map. In 1676 the mission of La Montagne was opened on the site of the present Séminaire de Montréal, where M. Belmont built a fort (1685). Alcohol traffic, major loss of mission housing by fire in 1694, and other factors necessitated the move of the first mission to one on the edge of the rivière des Prairies, near the Sault-au-Récollet rapids, in the north end in Montreal island. In 1717, the Compagnie de Saint-Sulpice de Paris was granted. a concession (~10.5 miles of frontage, ~9 miles deep) named seigneurie du Lac-des-Deux-Montagnes. In 1721, the Sulpicians moved the Sault-au-Récollet mission to two villages on seigneurie Lac-des-Deux-Montagnes territory; a first village to the west, which was their former hunting grounds and came to be called Kanesatake, was assigned to the Mohawks, and, later, a village to the east was assigned to the Algonquins and the Nipissings 

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