He was Minister of the Colonies in the French Cabinet headed by Léon Bourgeois between 1895 and 1896.

He was active in the debate over the 1905 French law on the Separation of the Churches and the State, to which he proposed an amendment.

[2] He was also active in the promotion of legislation to make pension contributions compulsory.

He played the dominant role in organizing the erection of the controversial statue of Ernest Renan in Tréguier.

[1] Marcel Guieysse, one of his sons, became a militant Breton nationalist and collaborator during World War II.