His work focused on the economy and society of the Ancien Régime, as well as diplomatic history during the 17th century, particularly the reigns of Louis XIII and Cardinal Richelieu.
Appointed archivist at the Archives of the Empire in 1869, his career began with the publication of his thesis under the title Études sur l’industrie et la classe industrielle à Paris aux XIIIe et XIVe siècles (1877). This work, comprised largely of unpublished documents, opened up a new field of study[4] and became a reference for over fifty years. Romanist Gaston Paris praised it as "a remarkable piece of scholarship that brought the history of 13th- and 14th-century Paris to life."[5]
Twenty years later he supplemented this book by a collection of Documents relatifs à l'histoire de l'industrie et du commerce en France (2 volumes, 1898–1900), and in 1897 he published L'économie sociale de la France sous Henri IV, a volume containing the results of very minute research. He did not, however, confine himself to economic history. His Le Père Joseph et Richelieu (1894),[6] though somewhat frigid and severe, is based on a mass of unpublished information, and shows remarkable psychological grasp.[4]
Founding of the Revue historique (1876)
In 1876, Gustave Fagniez co-founded the Revue historique with Gabriel Monod. The journal’s first article is considered the manifesto of the methodical school of history[7]. Fagniez later compiled articles on diplomatic history into his two-volume Le Père Joseph et Richelieu, which won the Grand prix Gobert in 1895.
Fagniez resigned from the Revue historique in 1881, protesting its attacks on the Church. He eventually joined the conservative Revue des questions historiques[8].
Later years
By the late 19th century, personal tragedies, including the death of his daughter Alice in 1894, led Fagniez to embrace his Catholic faith. He collaborated on social reform projects such as workers’ unions and urban gardens. Fagniez also became involved with the monarchist Action Française, contributing to its educational effort the Institut d'Action française.
Gustave Fagniez was elected to the Académie des Sciences Morales et Politiques in 1901 and served as its president in 1913. His body of work is celebrated for its rigor and historical depth.
Publications
Études sur l’industrie et la classe industrielle à Paris aux XIIIe et XIVe siècles (1877)
Le Père Joseph et Richelieu (1894)
L'Économie sociale de la France sous Henri IV (1897)
Corporations et syndicats (1904)
La Femme et la société française dans la première moitié du XVIIe siècle (1929)