Jan Kowalewski - Polish-Soviet War

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. During his service there, he managed to break the codes and ciphers of the army of the West Ukrainian People's Republic and General Anton Denikin's White Russian forces. Though his discovery was due to accident and boredom (he had to spend all night segregating radio intercepts and discarding the encrypted ones), it was 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 decoration, the Silver Cross of the Virtuti Militari.