 After working on legal questions for the Ministry, Pétillon became "chef de cabinet" (aide) to the minister Paul Tschoffen and for his successors in the ministry, including Albert de Vleeschauwer.In this capacity he supervised the creation of the Colonial Lottery in 1934.In February 1939, Pétillon asked to be posted to the Belgian Congo and received a position as "chef de cabinet" for the Governor-General, Pierre Ryckmans.