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.

His ancestors had been deported to Russia from their home in Lithuania (former Nowogródek Voivodeship region, now in Belarus) for participating in the January 1863–64 Uprising, for which a major part of their estate was confiscated.

In Vilnius, Pilecki attended a local school and joined the underground Polish Scouting and Guiding Association (Związek Harcerstwa Polskiego, ZHP).

[9][6] Following the outbreak of World War I, in 1916 Pilecki was sent by his mother to a school in the Russian city of Oryol, located safer in the East than Vilnius.

[6] In 1918, following the outbreak of the Russian Revolution and the defeat of the Central Powers in World War I, Pilecki returned to Vilnius, then outside the control of the Polish government, and joined the ZHP section of the Self-Defence of Lithuania and Belarus, a paramilitary formation under Major General Władysław Wejtko.

[9][6] The militia disarmed the passing German troops and took up positions to defend the city from a looming attack by the Soviet Red Army.

[1] He briefly enrolled with the Faculty of Fine Arts at Stefan Batory University but was forced to abandon his studies in 1924 due to both financial issues and the declining health of his father.

[6] Włodarkiewicz and Pilecki were among the many soldiers who did not follow the order of Commander-in-Chief General Edward Śmigły-Rydz to retreat through Romania to France, instead opting to stay underground in Poland.

Włodarkiewicz became its leader, while Pilecki became TAP's organizational head as it expanded to cover Warsaw, Siedlce, Radom, Lublin, and other major cities in central Poland.

[13]: 78  To stop him, Pilecki went to Colonel Stefan Rowecki, chief of a rival resistance group, the Union of Armed Struggle (Związek Walki Zbrojnej, ZWZ), which called for equal rights for Jews, gathered intelligence on German atrocities, and delivered it by courier to the Western Allies in an attempt to gain their involvement.

[13]: 78 Pilecki called for TAP to submit to Rowecki's authority, but Włodarkiewicz refused and issued a manifesto that the future Poland had to be Christian, based on national identity, and that those who opposed the idea should be "removed from our lands".

[14] In August, Włodarkiewicz announced at a TAP meeting that they would, after all, join the mainstream underground with Rowecki – and that it has been proposed that Pilecki should infiltrate the Auschwitz concentration camp.

[6][17]: 117–126 As part of his duties, Pilecki secretly drew up reports and sent them to Home Army headquarters with the help of inmates that had been released[clarification needed] or escapees.

The first dispatch, delivered in October 1940, described the camp and the ongoing extermination of inmates via starvation and brutal punishments; it was used as the basis of a Home Army report on "The terror and lawlessness of the occupiers".

[9] In 1942, Pilecki's resistance movement was also using a home-made radio transmitter to broadcast details on the number of arrivals and deaths in the camp and the conditions of the inmates.

It broadcast from the camp until the autumn of 1942, when it was dismantled by Pilecki's men after concerns that the Germans might discover its location because of "one of our fellows' big mouth".

[6][19]: 191–197  To avoid the worst outcome, Pilecki decided to break out of the camp with the hope of convincing Home Army leaders that a rescue attempt was a valid option.

Later, they reached the Polish resistance safe house near Bochnia, owned, coincidentally, by commander Tomasz Serafiński—the very man whose identity Pilecki had adopted for his cover in Auschwitz.

[9][13]: 283–302 [15]: 399  At one point during the journey, German soldiers attempted to stop Pilecki, firing at him as he fled; several bullets passed through his clothing, while one wounded him without hitting either bones or vital organs.

Even if the initial attack were successful, the resistance lacked sufficient transport capabilities, supplies, and the shelter that would be required for the rescued inmates.

[13]: 490 When the Warsaw Uprising broke out on 1 August 1944, Pilecki volunteered for service with Warszawianka Company [pl] of Kedyw's Chrobry II Battalion.

[6] After many officers were killed in the early days of the uprising, Pilecki revealed his true identity and accepted command of the 1st "Warszawianka" Company deployed in Warsaw's Śródmieście (downtown) district.

He was sent to Oflag VII-A, a prison-of-war camp for Polish officers located north of Murnau, Bavaria, where he remained until the prisoners were liberated on 29 April 1945.

[9][6][20]: 213 In July 1945, Pilecki joined the military intelligence division of the Polish II Corps under Lieutenant General Władysław Anders in Ancona, Italy.

In October 1945, as relations between the government-in-exile and the Soviet-backed regime of Bolesław Bierut kept deteriorating, Pilecki was ordered by Anders and his intelligence chief, Lieutenant Colonel Stanisław Kijak, to return to Poland and report on the prevailing military and political situation under Soviet occupation.

Anders ordered him to leave Poland, but Pilecki was reluctant to comply because he had a family in the country and his wife was unwilling to emigrate with their children, as well as due to a lack of a suitable replacement.

Pilecki denied the assassination charges, as well as espionage, although he admitted to passing information to the II Corps, of which he considered himself an officer and thus claimed that he was not breaking any laws.

The first in English was Józef Garliński's Fighting Auschwitz: The Resistance Movement in the Concentration Camp (1975), followed by M. R. D. Foot's Six Faces of Courage (1978).

[9] In 2010, Italian historian Marco Patricelli wrote a book about Witold Pilecki, Il volontario (2010), which received the Acqui Award of History that year.

"[18]: xv–xvii  Historian Norman Davies wrote in the introduction to the same translation: "If there was an Allied hero who deserved to be remembered and celebrated, this was a person with few peers.