Maksymilian Ciężki

During the German invasion of Poland in September 1939, Ciężki escaped to France to continue work on breaking Enigma ciphers.

In the 1930s, Ciężki, as an army captain, was chief of the Polish General Staff Cipher Bureau's German section (Biuro Szyfrów-4, abbreviated BS-4).

In March 1943, now-Major Ciężki, Lt. Col. Langer, Lt. Antoni Palluth and civilians Edward Fokczyński and Kazimierz Gaca were betrayed by their French guide and captured by the Germans as they attempted to cross from German-occupied France into Spain.

They convinced their interrogators that, while the Poles had had some success with solving the Enigma early on, changes introduced by the Germans just before the start of the war had prevented any further decryption.

[2] Palluth, Fokczyński and Gaca — according to Col. Stefan Mayer, prewar chief of the intelligence department in Section II of the Polish General Staff — likewise "were acquainted to the last detail with the... breaking [of] Enigma.