Gustave Bertrand was the head of the Bureau of French Military Intelligence responsible for Signals Intelligence before World War 2. It was his agency that brought in Hans-Thilo Schmidt, the German spy who fed priceless secrets including details of the military version of Enigma, enabling the Poles, the French and the British to glean war-winning intelligence during the conflict.
Yet Bertrand himself has remained an enigmatic character. He gave the Polish codebreakers a home after they were ejected from Poland in 1939, and somehow managed to keep them safe even after France was invaded in 1940. The ambiguous position of Bertrand under the Vichy régime is hard to explain, and the picture becomes even murkier after 1942. Bertrand has been criticised for bungling the evacuation of the Poles: to what extent was Bertrand, who was himself later arrested but mysteriously released within days, playing a double game? How safe was the Enigma secret in his hands?
In 2016 a newly-declassified archive of Gustave Bertrand’s files was opened to inspection. These papers suggest a more positive verdict on Bertrand and his ability to play both sides in a dangerous game which ultimately led to Allied victory in the war. The full story will appear in my book about Bertrand and the Polish code-breakers, X, Y and Z – the real story of how Enigma was broken.