In 1929 Zdzisław Krygowski, a professor at the University of Poznań, organised a secret course on cryptology for the best students of mathematics. Krygowski, who came from the famous Lviv school of mathematics, was approached to do so by the Cipher Bureau of the Polish Army, which decided to use mathematics to break foreign codes. Three mathematicians were selected from the course participants: Marian Rejewski, Henryk Zygalski and Jerzy Różycki. Not long after, they had a chance to come face-to-face with the Enigma code.