Born in Ghent, where he was taught before completing his training in Brussels, in 1883 Vanaise became one of the founding members of the group LesVingt.Influenced by Flemish and later by Dutch art, following a visit to the Low Countries in early 1878, but also by contemporaries such as Jan Van Beers, Vanaise moved to Paris in August 1878. He spent two years there and painted his first large history paintings, which he began to exhibit at the Salon.
