Gailliard attended the College of Saint Louis (Bruges) and the minor seminary in Roeselare where he had Guido Gezelle as a teacher. When his father died in 1864, he took over the family’s printing and bookbinding business. He published Gezelle's magazine Rond den Heerd (By the Fireside), La Flandre, De Halletoren and a number of other magazines and books. He co-wrote Table analytique and Glossaire Flamand with Gilliodts. In December 1884 he was appointed deputy governmental archivist in Bruges. He was a founding member of the Royal Academy for Flemish Linguistics and Literature (founded on 08.07.1886) and from 1904 onwards the secretary of its Permanent Committee for Medieval Literature. Between 1894 and 1905 he worked on De Keur van Hazebroek (5 volumes).
Gailliard and his wife (Photo Collection Antwerp, Letterenhuis)