Pichon is renowned for betraying the French, Acadian and Mi’kmaq forces by providing information to the British, which led to the fall of Beauséjour.

"[2] During Father Le Loutre's War, Pichon entered the service of secretary for Jean-Louis de Raymond [fr],[3] latterly reputed to be a place-seeker, who had been appointed Governor at the Fortress of Louisbourg and Île-Royale (New France) in 1751.

[4][5] Pichon retreated to London in 1757, where he entered on an affair with the French novelist Jeanne-Marie Leprince de Beaumont, whose marriage had been annulled.

Never a master of the English language, in 1769 he moved to Saint Helier, Jersey (a remnant of the Norman conquest where French was spoken), in which place he died on 22 November 1781.

[6] His 1760 book on Cape Breton Island—Genuine letters and memoirs relating to the natural, civil, and commercial history of the islands of Cape Breton and Saint John : from the first settlement there, to the taking of Louisbourg by the English in 1758—published in both English and French shortly after the conquest of Louisbourg in 1758, was the first such history of that island.