Marian Rejewski (1905–1980) was a Polish mathematician and cryptologist who, in 1932, solved the Enigma machine, the main cipher machine then in use by Germany. While studying mathematics at Poznań University, Rejewski attended a secret cryptology course conducted by the Polish General Staff's Cipher Bureau, which he joined full-time in 1932. Rejewski and his two colleagues then developed an assortment of techniques for the regular decryption of Enigma messages, including the cryptologic "card catalog", the "cyclometer", and the cryptologic "bomb". Five weeks before the German invasion of Poland in 1939, they presented their results on Enigma decryption to their French and British counterparts. Their success jump-started British reading of Enigma in World War II, and the intelligence so gained contributed to the defeat of Nazi Germany. (Full article...)