Honourable Poland


In March 1939, after annexing Austria, Czechoslovakia and Lithuanian port of Klaipeda, German Foreign Minister, Joachim von Ribbentrop, reiterated territorial demands he made previously against Poland in his numerous discussions with Polish ambassador in Berlin, Józef Lipski. The Germans demanded the return of the Free City of Danzing (Gdańsk) and acceptance of the extraterritorial highway passage connecting East Prussia with the rest of Germany through Polish Pomerania region, known as Polish Corridor, that provided Poland with access to the Baltic Sea. In various discussion, Ribbentrop proposed that Poland joins anti-Comintern alliance and becomes Hitler's ally. The German demands were rejected by the Polish government, especially in view of the guarantees that were given by the British politicians who pledged Britain's support in the event of German aggression. Such guarantees were given to Polish Foreign Minister, Józef Beck, by Duff Cooper, Secretary For War and First Lord of the Admiralty, during his visit to the Polish seaport in Gdynia, in August 1938. These guarantees were repeated on March 31, 1939, when British Prime Minister Neville Chamberlain told the House of Commons that “in the event of any action which clearly threatened Polish independence, and which the Polish Government accordingly considered it vital to resist, His Majesty’s Government would feel themselves bound at once to lend the Polish Government all support in their power.” The French Government endorsed this pledge. After rejecting German demands once again in May 1939, Polish Minister of Foreign Affairs, Józef Beck, gave a landmark speech to the Polish nation in the Polish Sejm: “Peace is a precious and desirable thing. Our generation, blooded in wars, certainly deserves peace. But peace, like almost all things of the world, had its price, a high but a measuarable one. We in Poland do not know the concept of peace at any price. There is only one thing in the lives of men, nations and countries that is without price. That thing is HONOUR.”

As part of the Polish-British military alliance, in July 1939, the British cryptanalysts from Code and Cypher School (GC&CS) in London paid a visit to the Polish Cipher Bureau at Pyry, outside Warsaw. The purpose of their visit was to meet with the Polish mathematicians and cryptographers from Poznań University - Marian Rejewski, Jerzy Różycki and Henryk Zygalski – who worked under supervision of Major Gwido Langer and Maksymilian Ciężki, deciphering decryption techniques of the Enigma machines that were used in the German military communication. The Enigma machine was an electromechanical device which enabled its operator to type a message, then ‘scramble’ it using a letter substitution system generated by variable rotors and an electric circuit. The machine had a keyboard like a typewriter but instead of a normal roller and type it had a set of lightbulbs which lit up letters on a translucent panel. By pressing down on a key, one of the lights would come up but for a different letter than the one that had been pressed. The security of the system depended on Enigma machine settings that were changed daily, based on secret key lists distributed in advance, and on other settings that changed for each message. The receiving station had to know and use the exact settings of rotors employed by the transmitting station to successfully decrypt a message. In addition, the combination of the cipher was diversified by a plug-in system. Each day the plugs could be set differently which caused another change of the code. Used initially by large firms to protect their correspondence, in 1925 the Germans began the mass scale production of the military version of Enigma for the needs of the German Army. In January 1929, a commercial Enigma machine arrived to Poland by mistake and was passed to Ciphers Office of the Intelligence Department of the II Bureau of the General Staff in Warsaw, which in turn had links with the cryptologists working at the Mathematical Institute at the University of Poznań. In the late 1920s, Professor Zdzisław Krygowski was recruited by Maksymilian Ciężki to run a cryptology course and scoop out the best brains that could assist Polish military intelligence in cracking German codes. Maksymilian Ciężki, who was one of the tutors, chose eventually three most talented mathematicians, Marian Rejewski, Jerzy Różycki and Henryk Zygalski and set up a branch office of the Cipher Bureau in Poznań.

The breakthrough in deciphering Enigma machine came when Marian Rejewski used the mechanical combination theory (the theory of permutation), which led to the discovery of the mechanisms of functioning of the machine's particular parts, and then to devising methods of recreating the deciphering keys to the coded messages.262 Yet before the Poles could decode German messages, they received help in the form of documents conveyed between December 1931 and September 1932 by an officer of the French ciphers bureau, Captain Gustave Bertrand. The material came from a French spy, Hans Thilo Schmidt (codename 'Asche'), a member of the German Chiffrierstelle, and contained photographs of the military version of Enigma, a basic instruction manual and two out of date monthly deciphering tables. Asche did not however had access for reaching the most protected secret, that is the diagram of the inner mechanism and the wiring of the three co-called rotors of the military version of Enigma – the E Eins – the potential of which appeared to be unbreakable.263 Using the mechanical combination theory with the information received from Asche, Marian Rejewski and his colleagues broke the code of Enigma for the first time during the second week of January 1933, when they began reading the telegrams. In February 1933, the Cipher Office requested the 'AVA' firm, which was the major supplier of short-wave radio sets for the General Staff, to build replicas of Enigma. The deciphering proved increasingly difficult when in 1934 the Germans changed the arrangement of the inter-connecting plugs once every quarter, from February 1, 1936, they did so every month, from 1 October every day, and finally every eight hours. Furthermore, they introduced six different sets of deciphering keys and the number of crucial elements, rotors and connecting plugs grew too. In response, Marian Rejewski constructed a 'cyclometer' to catalogue the cycle structure of Enigma permutation. Jerzy Różycki determined the rightmost rotor in the German Enigma by exploiting the different turnover positions. For the Poles, learning the rightmost rotor reduced the rotor-order search space by a factor of 3 (the number of rotors). When in September 1938, the Germans introduced changes to the initial settings of rotors not every 24 hours but prior to the transmission of each telegram, the Poles completed work on a mathematical model of another device – the so called 'bombe' – which was effectively the equivalent of six Enigma machines coupled together. Using six sets of Enigma rotors, the 'bombe' replicated every position the rotors could be in, to produce an outcome - sometimes taking up two hours to determine the positions of the rotors. The 'bombe' produced by Polish mathematicians was speeding up the decryption process and was one of the first modern computers to be build. Zygalski also came up with another devise that helped to determine the setting of the rotors. Zygalski's device comprised a set of 26 perforated sheets for each of the, initially, six possible sequences for inserting the three rotors into the Enigma's machine scrambler. When on December 15, 1938, the Germans increased the number of rotors from three to five the number of possible rotor arrangements had jumped from 6 to 60. As a result, 60 perforated sheets were needed and production of such sheets was very time-consuming. Marian Rejewski wrote how the perforatedsheets device was operated: “When the sheets were superposed and moved in the proper sequence and the proper manner with respect to each other, in accordance with a strictly defined program, the number of visible apertures gradually decreased. And, if a sufficient quantity of data was available, there finally remained a single aperture, probably corresponding to the right case, that is, to the solution. From the position of the aperture one could calculate the order of the rotors, the setting of their rings, and, by comparing the letters of the cipher keys with the letters in the machine, likewise permutation S; in other words, the entire cipher key.” 264 265 266

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262 More on breaking Enigma: M. Rejewski, Matematyczne podstawy rozwiązania niemieckiego szyfru maszynowego „Enigma”, pp. 369-393; W. Kozaczuk, W kregu Enigmy (Warsaw, 1979), pp. 52-59, 66-81 quoted in Jan Stanisław Ciechanowski, “Cryptographic Cooperation – Enigma”, p. 444 quoted in Intelligence Co-operation between Poland and Great Britain during World War II. Vol. I: The Report of the Anglo-Polish Historical Committee, op.cit. »

263 Ibid. »

264 Marian Rejewski, "The Mathematical Solution of the Enigma Cipher," Appendix E to Władysław Kozaczuk, Enigma, 1984, p. 289 »

265 Further reading: Z J Kapera, The triumph of Zygalski’s sheets: the Polish Enigma in the early 1940 (The Enigma Press, Krakow, 2015). »

266 Further reading: Dermot Turning, X, Y & Z: The Real Story of How Enigma Was Broken (History Press, 2018 »