While most people only credit Alan Turing for cracking of the Enigma, it is important to recognize the critical role that Marian Rejewski in paving the way for the Allies’ success.
In the early days of the war, Rejewski along with the Polish Cipher Bureau were able to identify that each letter in the ciphertext was linked to a chain of letters, thus allowing them to deduce that a relationship lied between the letters. This discovery removed the mystery surrounding the aptly named Enigma as they could now discern a pattern. If a pattern is present, then it can be concluded that there was a process taken to produce that which also means that, armed with logic and a lot of hard work, the steps in that process can be deduced. Had Rejewski not made this discovery, it can be argued that Turing would never have been able to crack the Enigma as it gave him a direction to pursue and a starting position of where to do that from.
In addition to this, Rejewski’s creation of the first bomba allowed Turing to understand the importance of mechanizing the cryptanalysis of the Enigma. By using a computer to solve the Enigma, it allowed the Allies to be more efficient. And so, when Turing was finally able to crack the Enigma, due to the time saved, the information deciphered was still useful and so they were able to anticipate and prepare for Germany’s attacks.
Although Singh argues that German overconfidence is the primary reason that the Allies were able to crack the Enigma, the principal reason for the Allies success was because of Rejewski. His creativity and innovative thinking was the breakthrough that allowed the Allies to ultimately break the Enigma.
