Louis Catherin Servant was born at Grezieu-le-Marché, France, on 25 October 1808. He came from a rural peasant background. His parents, Antoinette Blanchard and her husband, Jean-Antoine Servant, were small landholders in a village outside Lyons. Servant was strongly influenced by the tide of revivalist religious zeal which swept France in the aftermath of the revolution. In 1829 he entered the seminary of St Irenaeus at Lyons and was drawn into the circle of young priests and brothers who founded the Society of Mary in 1836. He was accepted as a volunteer for the newly established mission to the South Seas, and set sail on the Delphine on 24 December 1836. With Bishop J. B. F. Pompallier and Brother Michel Colombon, he stepped ashore at the Hokianga Harbour on 10 January 1838 to begin the Catholic missionary effort in New Zealand.
Servant was an unassuming, hard-working and single-minded missionary. Based first at Papakauwau on the south side of the Hokianga, then at Pūrākau opposite, he rapidly mastered the Māori language and, with Fathers Maxime Petit and Claude-André Baty, built up the nucleus of the present Hokianga Catholic community.
The Catholic missionaries' message was most readily received by tribes alienated from the Protestant missions, which were already well established in the area. The prophet leader Papahurihia and his followers saw the French Catholics as natural allies in a common cause against the Protestant community at Hokianga. Despite his abhorrence of the 'gross errors' of the prophet's teachings, Servant found himself obliged to accept Papahurihia's offer of association. Few Pākehā were thus privileged. Servant's writings, as a result, are among the few written sources of information about the prophet.
His ethnographic writings are marked by a persistent curiosity to understand the society in which he found himself. His notes, written for his Marist superior in Lyons between 1839 and 1842, have been published in English as Customs and habits of the New Zealanders (Wellington, 1973). They provide the most complete account of Māori life in one area that survives from this period. Servant was careful to separate what he had seen from things he had only heard about, and to distinguish between the Hokianga and other areas. His account shows a lively intelligence and a keen eye for observation. Servant's poverty made him more dependent than most Europeans on the local Māori. His view is remarkable for its honesty, and for the comparative reticence of its Eurocentric judgements.
Servant was not a leader, nor a firebrand evangelist. Reserved and bookish by nature, living in conditions of isolation and poverty, he cut a wan and solitary figure. At a debate with the Anglican missionary Henry Williams, in 1841, 'Father Servant, thin, tall, dry, emaciated and pale as a sheet, seemed a runt alongside the large and fresh-faced Williams,…a prosperous-looking, well fed father of 10 children', according to his fellow missionary A. M. Garin. Nevertheless the power and fluency of Servant's speech impressed his Māori congregation. Occasionally there are glimpses of fire beneath his piety. In 1840, writing to his Marist superior, Servant harshly criticised Pompallier's leadership of the mission, accusing the bishop of mistreating his priests and brothers.
In 1842, after four years at Hokianga, Servant was ordered to the island of Futuna to replace the martyred Father Pierre Chanel. During Servant's 13 years there the island became a flourishing Catholic community. Servant endured deafness, elephantiasis and possibly cholera, and returned to Sydney in mid 1855 to recover his health. By October 1855 he was off to Upolu in Samoa. Renewed illness caused him to be recalled to Sydney in 1859. En route he stopped at Futuna to gather information for the beatification of Chanel, and is said to have died suddenly after saying Mass on the morning of 8 January 1860. His tomb is in the church of Our Lady of the Martyrs on Futuna.