From the beginning of his priestly ministry in December 1700, Louis-Marie envisioned a Congregation ready to go anywhere to teach catechism to the peasants, the poor, and the children. During his 15 years of missionary life, Montfort had priest collaborators like Mr. BastiÃ¨re or Gabriel Ollivier who accompanied him for several years, but were not so steady. Around 1712, in La Rochelle, he wrote a Rule for the Missionary Priests of the Company of Mary, a rule where teaching of catechism to the children has an important place. It was not until February 1715 that this Company had the first priest: Adrien Vatel (1680-1748), a young Norman priest, a former student of the Seminary of the Holy Spirit of St. Claude Poullart des Places, but he did not commit himself with vows until 1722. In September 1715, a young priest of the diocese of La Rochelle, RenÃ© Mulot (1683-1749), despite his poor health, agreed to join the Father of Montfort. He became the 1st Superior General of the Company of Mary in 1722.
In 1705, in a church of Poitiers, Louis Marie called a young man of 18, Mathurin Rangeard (1687-1760), to follow him. Mathurin became his constant companion in the missions, and he continued this ministry until his death in 1760. Other brothers such as John, Peter, Nicolas, Jacques Philippe, Gabriel, Louis, also joined Montfort to help him. At the Pentecost 1715, according to tradition, four of them, Louis Philippe, Gabriel and Nicolas, pronounced their vows of obedience and poverty forming the nucleus of the Brothers of the Holy Spirit. Mathurin Jacques, out of scruple, did not dare take that step, even though they were devout followers of Montfort. In 1715, Montfort, concerned with the pastoral plan of Mgr. Champflour, Bishop of La Rochelle, asked some brothers to work in the charitable school at La Rochelle and at Nantes. In his testament of 27 April 1716, Montfort gave a considerable place to the brothers and envisaged that some of the brothers work in the charitable schools.