He worked with the British Special Operations Executive (SOE) giving them information about the Germans by travelling to Spanish Morocco.

The group helped refugees flee to Switzerland, sent information to the British via their consul in Geneva, and sabotaged German materiel.

She was later suspected of having betrayed Jean Moulin, one of the best-known members of the French Resistance, but Devigny always defended her vehemently against this charge.

On the night of 24–25 August, when conditions for escape were optimal, Devigny and another prisoner who had recently been placed in his cell climbed out a skylight, using a rope made from a blanket and a mattress cover and a grappling hook fashioned from the frame of an old lantern, made their way across a roof and descended to the courtyard.

Devigny eluded German search parties and fled to Switzerland with the help of comrades in the Resistance.

He retired in 1971 after President Georges Pompidou appointed Alexandre de Marenches as head of the intelligence services.

He considered entering politics, but decided not to "when I realized the backstabbing was far worse than anything I'd ever encountered in secret warfare".