Born in Mons on 15th July 1830, Leopold Devillers embraced a teaching career at the École moyenne before becoming an archivist. Entering the State Archives in Mons on 1st October 1853, he became assistant curator in 1858 before succeeding Augustin Lacroix as curator in 1869. He remained leader of this institution until 1898. He devoted much of his time writing inventories of the institution's primary funds (archives of Hainaut, maps and plans, archives of the City of Mons, etc.). Due to the disappearance of some of the archives in May 1940, many of these inventories are now considered precious. Léopold Devillers also published a large number of previously hidden documents on local history (accounts, orders, charters, etc.). Many historical works focus specifically on his hometown and Hainaut. He wrote biographies on a variety of outstanding figures of Hainaut for the Biographie Nationale de Belgique. He actively participated in cultural life as a member of numerous Belgian and foreign intellectual societies. A founding member of the Cercle archéologique de Mons (an archeology club) in 1856, he was its president for 46 years. A member of the Belgian Société des Bibliophiles in Mons and the Société des Sciences, des Arts and des Lettres of Hainaut, he contributed to their work with great dedication. On careful examination of the archives, he encouraged the historians of these societies to turn to alternative sources, not solely narrative sources. He was very active in local society as a member of various charities and committees (the Commissions des hospices civils, the Bureau de bienfaisance of Mons, and the Comité de patronage des habitations ouvrières). He died on 22nd May 1910, leaving a large void among his colleagues. This is clear to see simply by reading the eulogies delivered by various personalities at his funeral and which are published in volume 39 of Annales du Cercle archéologique of Mons.
Joseph CUVELIER et Maurice-Aurélien ARNOULD, Léopold Devillers dans Biographie nationale. Bruxelles, Emile Bruylant, 1956. t.29, col. 553-557 ; Émile DONY, In mémoriam Léopold Devillers 1830-1910. Ses funérailles. Sa bibliographie dans ACAM, t. 39, 1910, p. 1-54 ; Ernest MATTHIEU, Léopold Devillers : notice biographique. Anvers, Imprimerie J. Van Hille-De Backer, 1911. (Taken from Belgium’s Bulletin de l’Académie royale d’Archéologie).