Bonnier de La Chapelle was born in Algiers, son of a French journalist who was a monarchist and a protester against fascism. Bonnier was involved with a royalist group that wanted to make the pretender to the French throne, the Count of Paris, the King of France. He studied at the Lycée Stanislas in Paris after France's surrender to Nazi Germany, and attended a demonstration of anti-German students on Armistice Day 11 November 1940 at the Arc de Triomphe. He then joined the free zone by illegally crossing the border. He returned to Algiers (where his father was a journalist for The Algerian Dispatch) and visited the Youth Camps. After obtaining his degree in 1942, he was surprised by the Allied landings on 8 November 1942 during (Operation Torch). A monarchist and ardent anti-Vichyiste, he regretted that his comrades who had participated in Operation Torch, enabling the success of the landing, had not asked him to participate.