Jean-Georges Willmar attended secondary school at the Royal College in Luxembourg from 1772, then at the University of Louvain.
When Luxembourg was occupied by French Revolutionary troops, the Armies of the North and of the Sambre and Meuse established an arrondissement administrative council, initially in Saint-Hubert, consisting of 9 members and an "Agent national".
When Luxembourg was incorporated into the Département des Forêts, Willmar was appointed president of the criminal tribunal.
As governor, he also reported to The Hague on the ever-rising discontent of the people over taxes, seen as too high and unfair.
There was however, little will to compromise on the part of the Dutch King, and Prince William II was imposed as governor of the southern provinces.