Before the war, a team of Polish cryptanalysts had in fact figured out the workings of the Enigma. Small, vulnerable nations surrounded by big potential enemies—Poland is bordered by Russia and Germany—tend to be hypervigilant about their neighbors, and the Polish Cipher Bureau was remarkably good. The Poles broke the Enigma during the 1930s, in part thanks to a German who passed schematics and decrypted messages to French intelligence, who passed it to them, and to a commercial model they obtained.
I always thought Engima was broken by Alan Turing at Bletchley Park. Turns out he took what the Poles knew and refined their work.
