Witold Pilecki (13 May 190125 May 1948; ; codenames Roman Jezierski, Tomasz Serafiński, Druh, Witold) was a Polish soldier (cavalry officer) during the Second Polish Republic, the founder of the Secret Polish Army (Tajna Armia Polska) resistance group in German-occupied Poland in November 1939 and a member of the underground Home Army (Armia Krajowa), which was formed in February 1942. As the author of Witold's Report, the first intelligence report on Auschwitz concentration camp, Pilecki enabled the Polish government-in-exile to convince the Allies that the Holocaust was taking place.