PC Bruno was a Polish-French intelligence station that operated outside Paris during World War II, from October 1939 until June 9, 1940. It decrypted German ciphers, most notably messages enciphered on the Enigma machine.
PC Bruno operated at the Chateau de Vignolles in Gretz-Armainvillers, some 40 kilometers northeast of Paris, from October 1939 until June 9, 1940, well into the German invasion of France (May-June 1940). Bruno was headed by French Army radio-intelligence officer, Major Gustave Bertrand. Its personnel included 15 Poles, 50 Frenchmen, and 7 anti-fascist Spaniards who worked on Spanish and Italian ciphers.
In July 1939, the Polish General Staff's Cipher Bureau had turned over to French and British intelligence representatives information about the Polish achievements in breaking German military Enigma traffic. The British, working at Bletchley Park outside London, put considerable effort into mastering the reading of German Wehrmacht and Luftwaffe Enigma as World War II began in Poland, and during the "Phony War" before the Germans invaded France.
Most of the Polish Cipher Bureau's key personnel had managed to reach France by October 1939 and had been assigned to PC Bruno.
As late as December 1939, when the Cipher Bureau's chief, Lt. Col. Gwido Langer, and French Air Force Capt. Henri Braquenié were (December 3-7) visiting London and Bletchley Park, the British asked that the Polish cryptologists be turned over to them. Langer, however, took the position that they must remain where the Polish armed forces were being formed — on French soil.
Bletchley Park and PC Bruno worked together against the German message traffic with considerable success. In the interest of security, they themselves corresponded using the "unbreakable" Enigma cipher. Messages decrypted at Bruno included some that gave advance notice of planned German invasions of Denmark, Norway, Belgium and the Netherlands.
During the ensuing German invasion of France, Bertrand evacuated the Bruno personnel from Gretz-Armainvillers just after midnight on June 10, 1940. Two weeks later, on June 24, two days after the French-German armistice, he flew the 15 Poles and seven Spaniards in three planes to Algeria.
A couple of months later, in September 1940, Bertrand would secretly return them to southern (Vichy) France (France's unoccupied "Free Zone"), to Uzès on the Mediterranean coast. There, at a facility codenamed "Cadix," they would work at breaking ciphers for over two years until November 9, 1942.
 See also
|Methods and technology|
Chief of Radio Intelligence
Chief of German Section
German Section cryptologists Wiktor Michałowski
Chief of Russian Section
Russian Section cryptologist
- "PC" is an abbreviation for the French term Poste de Commandement — "Command Post."
- Kozaczuk, 1984 Enigma, pp. 84, 99.
- Władysław Kozaczuk, Enigma: How the German Machine Cipher Was Broken, and How It Was Read by the Allies in World War Two, edited and translated by Christopher Kasparek, Frederick, MD, University Publications of America, 1984, ISBN 0-89093-547-5.
- Gustave Bertrand, Enigma ou la plus grande énigme de la guerre 1939–1945 (Enigma: the Greatest Enigma of the War of 1939–1945), Paris, Librairie Plon, 1973.
- Stephen Budiansky, Battle of Wits, a general account of World War II cryptology.
- F.H. Hinsley, ed., British Intelligence in the Second World War, 4 volumes, London, Her Majesty's Stationery Office.
- F.H. Hinsley and Alan Stripp, eds., Codebreakers: the Inside Story of Bletchley Park, Oxford University Press, 1993, ISBN 0-19-820327-6: a volume of recollections.