Fr Marie-Humbert Vicaire joined the Order of Preachers in 1928. While studying at the Saulchoir in Belgium he acted as secretary to Fr Mandonnet (d. 1936). In 1937 he was called to the University of Fribourg (Switzerland) to occupy the chair of Church History founded by the same Fr Mandonnet. There he published, under the latter's name, the two volumes of St Dominic: The Idea, the Man and the Work.