Polish Enigma doubles

Enigma "doubles" were machines produced by the Polish Cipher Bureau, based on Marian Rejewski's reconstruction of the German Enigma machine's wirings.

Built in Poland
In February 1933, the Polish Cipher Bureau ordered fifteen "doubles" of the military Enigma machine from the AVA Radio Manufacturing Company, in Warsaw. Ultimately, about seventy such units would be produced.

Precious gift
In 1939, two Enigma doubles were sent to Paris and London. Until then, German military Enigma traffic had defeated the British and French, and they had faced the disturbing prospect that German communications would remain "black" to them for the duration of the coming war.

Built in France
After Germany invaded Poland in September 1939 and key Polish Cipher Bureau personnel evacuated to France, the Cipher Bureau resumed its interrupted work at PC Bruno, outside Paris. The Poles had only three Enigma doubles to work with, and these were wearing out from round-the-clock use. French Army intelligence officer Gustave Bertrand ordered parts for forty doubles from a French precision-mechanics firm. Manufacture proceeded sluggishly, however, and it was only after the fall of France and the opening of underground work in southern France's Free Zone in October 1940 that four machines were finally assembled.