The Cordemoy sons were, like their father, closely linked to Bossuet’s circle and thus, even after the dramatic rupture of July 1696, with Fénelon. After the revocation of the Edict of Nantes, in 1685, Jacques de Cordemoy formed part of a mission, led by Fénelon, to convert the Protestants of Saintonge. Fénelon arrived in Saintes on 15 December 1685, he returned to Paris in June 1686, but Jacques seems to have stayed on for ten years, or more, based at the port of La Tremblade, on the mouth of the Seudre, south of Rochefort, where Protestants gathered to embark for abroad. His impassioned reports survive from January 1693 to March 1694. Jean-Louis himself, promoted by Jérome Phélypeaux de Pontchartrain, minister de Marine, by his elder brother, Louis-Gerauld, was sent on a mission in 1700 to investigate the feasibility of floating logs by rivers from the Auvergne to the shipbuilding yards at the coast. He drew up a map of the area from Condat (Cantal), hard by Feniers, on the river Santoire, which joined the Rhue, and a parallel route from Valette, to the west, on the Sumène, also joining the Rhue, just before its junction with the Dordogne. A report was submitted in 1705. The project was approved by Vauban, but seems not to have been implemented.