On March 20, 1918 Wilby was transferred to the Chaumont-Porcien on Headquarters of the American Expeditionary Force, where he was appointed as a Chief of Engineer Intelligence Division in the Office of Chief of Engineers.
Through their descent from Louise and her mother, the princely family of Monaco now lays claim to the wealth and estates bequeathed by Cardinal Mazarin, including the Duchy of Rethel, and the Principality of Château-Porcien.
The Château de Doumely is a 15th-century fortified castle that dominates the countryside of Porcien, situated in the commune of Doumely-Bégny in the Ardennes département of France.