Thread by @GershomG

#OTD September 6, 1939: The man who hacked Enigma - the Nazi's "unbreakable" cipher - escapes from Warsaw on train east. In 1932, Marian Rejewski had done the supposedly impossible…
@sheeraf @ShiraOvide @ShiraOvide @mmagierowski @calderwalton @GCHQ @MilHistNow

To break Enigma, you had to figure out the wiring inside the machine's turning wheels. The number of possibilities came to 500,000,000,000, 000,000,000,000,000,000,000,000,000,000,000,000,000,000,000, 000,000,000,000,000,000,000,000,000,000,000,000.

Naturally, the Germans were sure no one could do this.
Rejewsk came up with the equations & did it in under 3 months at the end of 1932 for the Polish military's Cipher Office.

All of Britain's successes against Enigma, including Alan Turing's work, were based on Rejewski's pre-war success. Rejewski & colleagues shared their secret w/British colleagues in summer 1939 -

even so, Brits would have been stymied if Rejewski hadn't fled from Warsaw to eastern Poland to Romania to France. Impossible to know how many lives were saved by his work -

but they likely include all the Jews of the Middle East.
Read more in #War_of_Shadows
publicaffairsbooks.com/titles/gershom…