Witold Pilecki (13 May 1901 – 25 May 1948) was a Polish cavalry officer, intelligence agent, and resistance leader. He served as a Rotmistrz (captain) with the Polish Army in the Polish-Soviet War, Second Polish Republic, and World War II. He was also a co-founder of the Secret Polish Army (Tajna Armia Polska), a resistance group in German-occupied Poland, and later a member of the underground Home Army (Armia Krajowa). He was the author of Witold’s Report, the first comprehensive Allied intelligence report on Auschwitz concentration camp and the Holocaust.
During World War II, Pilecki volunteered for a Polish resistance operation that involved being imprisoned in the Auschwitz death camp in order to gather intelligence and later escape. While in the camp, he organized a resistance movement and informed the Western Allies of Nazi Germany’s Auschwitz atrocities as early as 1941. He escaped from the camp in 1943 after nearly 2 1/2 years of imprisonment. He took part as a combatant in the Warsaw Uprising in August–October 1944. He remained loyal to the London-based Polish government-in-exile after the Communist takeover of Poland, and he was arrested for espionage in 1947 by the Stalinist secret police (Urząd Bezpieczeństwa) on charges of working for “foreign imperialism”, a euphemism for British Intelligence. He was executed after a show trial in 1948. Information was suppressed about his exploits and fate until 1989 by the Communist regime in Poland.
via Wikipedia https://en.wikipedia.org/wiki/Witold_Pilecki