World War II: Polish resistance leader Witold Pilecki allowed himself to be captured by German forces and sent to Auschwitz to gather intelligence.

World War II or the Second World War was a global conflict between two coalitions: the Allies and the Axis powers. Nearly all of the world's countries participated, with many nations mobilising all resources in pursuit of total war. Tanks and aircraft played major roles, enabling the strategic bombing of cities and delivery of the first and only nuclear weapons ever used in war. World War II is the deadliest conflict in history, causing the death of 70 to 85 million people, more than half of whom were civilians. Millions died in genocides, including the Holocaust, and by massacres, starvation, and disease. After the Allied victory, Germany, Austria, Japan, and Korea were occupied, and German and Japanese leaders were tried for war crimes.

In Poland, the resistance movement during World War II was led by the Home Army. The Polish resistance is notable among others for disrupting German supply lines to the Eastern Front, and providing intelligence reports to the British intelligence agencies. It was a part of the Polish Underground State.

Witold Pilecki, known by the codenames Roman Jezierski, Tomasz Serafiński, Druh and Witold, was a Polish World War II cavalry officer, intelligence agent, and resistance leader.

Auschwitz, also known as Oświęcim, was a complex of over 40 concentration and extermination camps operated by Nazi Germany in occupied Poland during World War II and the Holocaust. It consisted of Auschwitz I, the main camp (Stammlager) in Oświęcim; Auschwitz II-Birkenau, a concentration and extermination camp with gas chambers, Auschwitz III-Monowitz, a labour camp for the chemical conglomerate IG Farben, and dozens of subcamps. The camps became a major site of the Nazis' Final Solution to the Jewish question.