 Construction of "Diderot" began on 26 December 1906 by Ateliers et Chantiers de la Loire in Saint-Nazaire and the ship was laid down on 20 October 1907.She was launched on 19 April 1909 and was completed on 1 August 1911.The ship was assigned to the First Division of the First Squadron ("escadre") of the Mediterranean Fleet when she was commissioned.