He reported about the state of Poland, its many competing resistance factions, and also about Germany's destruction of the Warsaw Ghetto and its operation of extermination camps on Polish soil that were murdering Jews, Poles, and others.

Emigrating to the United States after the war, Karski completed a doctorate and taught for decades at Georgetown University in international relations and Polish history.

Karski was featured in Claude Lanzmann's nine-hour film Shoah (1985), about the Holocaust, based on oral interviews with Jewish and Polish survivors.

He was transferred to the Germans as a person born in Łódź, which was incorporated into the Third Reich, and thus escaped the Katyn massacre of Polish officers by the Soviets.

There he joined the SZP (Służba Zwycięstwu Polski)—the first resistance movement in occupied Europe, organized by General Michał Karaszewicz-Tokarzewski, the predecessor to ZWZ, later the Home Army (AK).

[citation needed] In 1942, Karski was selected by Cyryl Ratajski, the Polish Government Delegate's Office at Home, to undertake a secret mission to see prime minister Władysław Sikorski in London.

[9] Based on Karski's microfilm, Polish Foreign Minister Count Edward Raczyński provided the Allies with one of the earliest and most accurate accounts of the Nazi Holocaust.

Raczyński's Note, addressed to the governments of the United Nations on 10 December 1942, was later published along with other documents in a widely distributed leaflet entitled The Mass Extermination of Jews in German Occupied Poland.

[12] Karski met with many other government and civic leaders in the United States, including Supreme Court Justice Felix Frankfurter, Cordell Hull, William Joseph Donovan, and Rabbi Stephen Wise.

Karski presented his report to media, bishops of various denominations (including Cardinal Samuel Stritch), members of the Hollywood film industry and artists, but without result, as most people could not comprehend the scale of extermination that he recounted.

[citation needed] In 1944, Karski published Courier from Poland: The Story of a Secret State (a selection was featured in Collier's magazine six weeks before the book's publication).

[17][18] According to historian Adam Puławski, Karski's main mission as a courier was to alert the government-in-exile of the conflicts within Polish underground movements.

Karski's 1942 report on the Holocaust and the London Polish government's appeal to the United Nations were briefly recounted by Walter Laqueur in his history The Terrible Secret: Suppression of the Truth about Hitler's Final Solution (1980).

[23] Unhappy with how he was presented in the film, Karski published an article, later a book, Shoah, a Biased Vision of the Holocaust (1987), in the French journal Kultura.

He argued for another documentary to include his missing testimony and also to show more of the help given to Jews by many Poles (some are now recognized by Israel as the Polish Righteous among the Nations).

In 2010, French author Yannick Haenel published a novel Jan Karski, drawn from the courier's World War II activities and memoir.

[22] Karski's wartime book was re-published posthumously by Georgetown University Press as My Report to the World: The Story of a Secret State (2013).

It featured a discussion of Karski's legacy by School of Foreign Service Dean Carol Lancaster, Georgetown University Board Chair Paul Tagliabue, former Secretary of State Madeleine Albright, former National Security Advisor Zbigniew Brzezinski, Polish Ambassador Ryszard Schnepf, and Rabbi Harold S.

He struggled as a refugee, holding low-level jobs after settling in Washington, D.C., in 1960 near his brother Jan. Marian Kozielewski committed suicide there in 1964 and is buried at Mount Olivet Cemetery.

[33] Additional benches, which were made by the Kraków-based sculptor Karol Badyna, are located in Kielce, Łódź, and Warsaw in Poland, and on the campus of Tel Aviv University in Israel.

Shortly after his death, the Jan Karski Society was established, initiated by his close friend, collaborator and biographer, Professor Waldemar Piasecki.

The list of laureates includes: Elie Wiesel, Shimon Peres, Lech Walesa, Aleksander Kwaśniewski, Tadeusz Mazowiecki, Bronisław Geremek, Jacek Kuroń, Adam Michnik, Karol Modzelewski, Oriana Fallaci, Dagoberto Valdés Hernández, Stanisław Dziwisz, Tygodnik Powszechny magazine, the Hoover Institution, and the United States Holocaust Memorial Museum.

In addition, they wanted to promote educational activities, including workshops, artistic performances, and a reprint of his 1944 book, Story of a Secret State.

[36] On 23 April 2012, US President Barack Obama announced that Karski would receive the country's highest civilian honor, the Presidential Medal of Freedom.

[37] The medal was awarded posthumously by President Obama on 29 May 2012 and presented to Adam Daniel Rotfeld, the former Foreign Minister of Poland and himself a Jewish Holocaust survivor.

Member of the Polish parliament Professor Tadeusz Iwiński recently openly criticized the president of Poland for inaction on Karski's behalf.

[citation needed] On 24 June 2014, the "Jan Karski Mission Accomplished" Conference took place in Lublin under the patronage of Professor Elie Wiesel, Nobel Peace Prize Laureate, Aleksander Kwaśniewski, President of Poland (1995–2005), Moshe Kantor, President of the European Jewish Congress, and Michael Schudrich, Chief Rabbi of Poland.

[42] Former Foreign Minister of Poland Władysław Bartoszewski, in his speech at the ceremony of the 60th anniversary of the liberation of the concentration camp at Auschwitz-Birkenau, 27 January 2005, said: "The Polish resistance movement kept informing and alerting the free world to the situation.

"[43] A full-length play on Karski's life and mission, Coming to See Aunt Sophie (2014), written by Arthur Feinsod, was produced in Germany and Poland.

A new play, My Report to the World, written by Clark Young and Derek Goldman, premiered at Georgetown University during the conference honoring Karski's centennial year.