Answer
Southern Vichy France served as the clandestine workplace of Marian Rejewski, a Polish mathematician. Rejewski played a pivotal role in breaking the Enigma code during World War II. He worked alongside fellow Polish cryptologists Jerzy Różycki and Henryk Zygalski in a secret operation known as the "Enigma Project." Their efforts significantly weakened the German military's communication system, providing valuable intelligence to the Allies.