The Polish Cipher Bureau's Last Stand

When Germany invaded Poland, the Polish cryptologists who had broken Enigma were evacuated east. Three of them — Rejewski, Rozycki, and Zygalski — made it to France and continued working from PC Bruno, a chateau near Paris. When France fell in 1940, they escaped again to unoccupied Vichy France, continuing to decrypt German messages. Rozycki died in 1942 when the ship carrying him back to France from Algeria was torpedoed. Rejewski and Zygalski eventually made it to Britain, only to be told they weren't cleared to work for Bletchley Park — the very people who had cracked Enigma were deemed a security risk and put to work on manual labor.