[1] Bertrand's intelligence associates had purchased documents pertaining to the Enigma machine from Hans-Thilo Schmidt (codenamed "Asché" by the French), an employee at the German Armed Forces' Cryptographic Agency.

In December 1932, then-Captain (later, General) Bertrand turned these documents over to the Polish Cipher Bureau's chief, Major Gwido Langer.

Asché's documents, according to cryptologist Marian Rejewski's testimony, proved in practice crucial to his mathematical solution of the military Enigma machine's wiring.

Bertrand was to learn of the Poles' success against Enigma only six and a half years later, at a trilateral Polish-French-British conference held in the Kabaty Woods, south of Warsaw, on 25 July 1939, just five weeks before the outbreak of World War II.

On 2 June 1944, four days before the D-Day Normandy landings, at an improvised airstrip in France's Massif Central, Bertrand, his wife and a Jesuit priest who served as a courier of the Polish Resistance climbed into a small, unarmed Lysander III aircraft that flew them to southern England.