When Sebastian Valfre joined the Oratory of Turin as a 22-year-old seminarian in 1651, the community was down to one member. By the time of his ordination the following year, three more priests had joined the Oratory; this was a sign of the great impact Fr. Valfre would have on the Church in Piemonte and beyond.
Fr. Valfre is known for his work with the poor, despite his attempts to work discretely and anonymously. He was particularly effective in his service of the poor during the famine of 1678-80 and the 17-week siege of Turin during the war between Piemonte and Louis XIV. He is still invoked as patron of military chaplains for his ministry to soldiers during the war.
As a confessor, Fr. Valfre was known for his attentiveness and compassion. Along with his promotion of Marian devotion and the Forty Hours, his work in the confessional is credited with a religious revival in Turin, and he served as confessor to the royal family of Piemonte. He declined appointment as archbishop of Turin out of humility.