3 May 1901 – 25 May 1948), known by the codenames Roman Jezierski, Tomasz Serafiński, Druh and Witold,[1] was a Polish World War II cavalry officer, intelligence agent, and resistance leader.

As a youth, Pilecki joined Polish underground scouting; in the aftermath of World War I, he joined the Polish militia and, later, the Polish Army. He participated in the Polish–Soviet War, which ended in 1921. In 1939, he participated in the unsuccessful defense of Poland against the invasion by Nazi Germany, the Slovak Republic, and the Soviet Union. Shortly afterward, he joined the Polish resistance, co-founding the Secret Polish Army resistance movement. In 1940, Pilecki let himself be captured[2]: 66 [3][4][5] by the occupying Germans in order to be voluntarily sent to the Auschwitz concentration camp and infiltrate it. At Auschwitz, he organized a resistance movement that eventually included hundreds of inmates, and he secretly drew up reports detailing German atrocities at the camp, which were smuggled out to Home Army headquarters and shared with the Western Allies. After escaping from Auschwitz in April 1943, Pilecki fought in the Warsaw Uprising of August–October 1944. Following its suppression, he was interned in a German prisoner-of-war camp. After the communist takeover of Poland, he remained loyal to the London-based Polish government-in-exile. In 1945, he returned to Poland to report the situation in Poland back to the government-in-exile. Before returning, Pilecki compiled his previous reports into Witold’s Report to detail his Auschwitz experiences, anticipating that he might be killed by Poland’s new communist authorities. In 1947, he was arrested by the secret police on charges of working for “foreign imperialism” and, after being subjected to torture and a show trial, was executed in 1948.