Lt. Col. Jan Kowalewski (23 October 1892 – 31 October 1965) was a Polish cryptologist, intelligence officer, engineer, journalist, military commander, and creator and first head of the Polish Cipher Bureau. He recruited a large staff of cryptologists who broke Soviet military codes and ciphers during the Polish-Soviet War, enabling Poland to weather the war and achieve victory in the 1920 Battle of Warsaw. Early life Jan Kowalewski was born 1892 in Łódź, Congress Poland, under rule of the Russian Empire. After graduating from a local trade school, between 1909 and 1913 he studied at the University of Liège in Belgium, where he graduated from the faculty of chemistry. World War I He returned to Poland in 1913, only to be mobilized for the Russian Army the following year, at the outbreak of World War I. He fought in various formations on the Belarusian and Romanian fronts as an officer of the Engineering and Signal Corps, and in December 1918 he was allowed to join the Polish unit formed under command of Gen. Lucjan Żeligowski out of Poles living in Russia. As chief of intelligence of the Polish 4th Rifle Division he crossed the Romanian border with the Division and reached Poland in May 1919. Polish-Soviet War A polyglot and amateur cryptologist, Kowalewski was initially attached to the staff of Gen. Józef Haller, fighting in Volhynia and Eastern Lesser Poland during the Polish-Ukrainian War for the city of Lwów. One day during his service there, Kowalewski was given some enciphered Bolshevik messages that had been intercepted, and within two days, he had deciphered them. They revealed the Bolsheviks' appreciation of General Anton Denikin's White Russian forces. He also managed to break the codes and ciphers of the army of the West Ukrainian People's Republic. He had to spend all night segregating radio intercepts and discarding the encrypted ones, it caused a major sensation among the staff. As a result, in July 1919 he was transferred to Warsaw, where he became chief of the Polish General Staff's radio-intelligence department. By early September he had gathered a group of mathematicians from Warsaw University and Lwów University (most notably, founders of the Polish School of Mathematics—Stanisław Leśniewski, Stefan Mazurkiewicz and Wacław Sierpiński), who were also able to break Russian ciphers. Though Kowalewski's contribution to Polish victory in the Polish-Soviet War remained a secret for over 70 years, he was awarded Poland's highest military