Chapman was still in prison when the Channel Islands were invaded by the Germans. While incarcerated he met Anthony Faramus. Following a letter in German which they concocted to get off the Island, they were transferred to Fort de Romainville in Paris. There, Chapman confirmed his willingness to act as a German spy. Under the direction of Captain Stephan von Gröning, head of the in Nantes, he was trained in explosives, radio communications, parachute jumping and other subjects in France at La Bretonnière-la-Claye, Saint-Julien-des-Landes, near Nantes, and dispatched to Britain to commit acts of sabotage.