In 1764, he was appointed by the Elector of Cologne, Maximilien-Frédéric, Count of Koningseck Rothefels, to travel with him to Frankfurt to help in the election and the coronation of the King of the Romans.
In addition to a work on the French branch of the “Gillès” family he was also responsible for several publications on the history of his family. He settled in Lille towards 1766.