- 13 April
- Alfred Wetzler taken to Auschwitz.
- Dionys Lenard from Slovakia escapes from Majdanek with news of what happened to Slovakian Jews.
- 20 June
- Kazimierz Piechowski, a Polish prisoner, and three or four others escape; they pass information to the Polish Home Army (AK).
- 30 June
- Rudolf Vrba taken to Auschwitz.
- 2 November
- Kazimirez Halori, a Polish prisoner, escapes and passes information to the Polish Socialist Party.
- Report entitled "Auschwitz–Camp of Death" published by Natalia Zarembina, another Polish escapee; it is later published in English in 1943 (London) and March 1944 (New York).
- 27 April
- Witold Pilecki, a Polish soldier, escapes. Witold's report is filed away by the British government with a note saying there was no indication as to the source's reliability. Jan Redzej and Edward Ciesielski escape with Pilecki and each compiles a separate report for the Polish Home Army.
- Stanislaw Chybinski, a member of the Polish Home Army, escapes and compiles the report "Snapshots of Auschwitz".
- 19 November
- Jerzy Tabeau (or Tabau) and Roman Cieliczko escape. They write a report in December 1943 and January 1944 that becomes known as the "Polish Major's report".
- 19 March
- Germany invades Hungary.
- 22 March
- The Washington Post and the New York Herald Tribune report the existence of gas chambers and crematoria at Auschwitz.
- 5 April
- Siegfried Lederer escapes to warn Jews in Theresienstadt and the Red Cross about the mass murder inside the camp.
- 7–11 April
- Vrba and Wetzler escape.
- 22 / 23 April
- Vrba and Wetzler arrive in Žilina, Slovakia.
- 24 April
- Vrba and Wetzler meet Dr Oscar Neumann of the Slovakian Jewish Council.
- 27 April
- Oscar Krasniansky completes a German translation of the Vrba-Wetzler report.
- 28 April
- A copy of the report is handed to Rudolf Kastner of the Budapest Aid and Rescue Committee. The first trainload of Hungarian Jews leaves for Auschwitz (preceding the mass deportations).
- c. 28 April
- Kastner gives a copy of the report to Geza Soos, Hungarian Foreign Ministry official; Soos gives it to Joszef Elias; Elias's secretary translates it into Hungarian and prepares six copies for Hungarian officials.
- 15 May
- Mass transports begin of Hungary's Jews to Auschwitz, at a rate of 12,000 a day.
- 27 May
- Arnost Rosin, a Slovakian Jew, and Czesław Mordowicz, a Polish Jew, escape from Auschwitz. They write a report about the killing of Hungarian Jews.
- 4 June
- The New York Times reports that a young Pole who escaped from Auschwitz described the gas chambers and said that Jews were being executed.
- 6 June
- Allied invasion of Normandy, France.
- mid June
- The Vrba-Wetzler report reaches the British and US governments.
- 15 June
- The BBC World Service reports that 4,000 Jews from the Theresienstadt concentration camp were killed in gas chambers at Auschwitz during March 1944. Rosin and Mordowicz (see 27 May) tell Oscar Krasniansky (see 27 April) that around 100,000 Hungarian Jews were killed on arrival at Auschwitz-Birkenau between 15 and 27 May, apparently with no knowledge of what was about to happen to them.
- 16 June
- The New York World Telegram repeats the BBC's information. Allen Dulles, Swiss director of the US Office of Strategic Services, sends the Vrba-Wetzler report to the US State Department.
- 17 June
- The Los Angeles Times repeats the BBC's information.
- 20 June
- 'The Washington Times Herald reports the same, courtesy of Reuters, while The New York Times offers further details. In Bratislava, Vrba discusses his report with Vatican legate Monsignor Mario Martilotti, who then sends a copy to the Vatican via Switzerland.
- 25 June
- The New York Times reports that "new mass executions" recently took place in Auschwitz.
- 30 June
- The Kastner train, carrying 1,684 Jews, leaves Hungary for Switzerland via Bergen-Belsen.
- 1–10 July
- Several newspapers report that, between April 1942 and April 1944, 1.5 to 1.7 million Jews were killed at Auschwitz (from the Vrba-Wetzler report).
- 7 July
- Hungarian government orders a halt to the deportations.
- 9 July
- Mass deportations end.