Jan Karski was a secret emissary of the Polish underground state who informed the Polish government-in-exile and Western leaders about the extermination of Jews that was taking place on Polish territory during World War II , especially the situation of the destruction of the Warsaw Ghetto, and the secretive Nazi extermination camps.
Following Russia's invasion Poland’s eastern territories in September, 1939, Karski found himself in Soviet captivity, together with thousands of Polish officers. Yet he managed to escape during transport, thus escaping the fate that met the majority of the Polish officers, who were mass-murdered in Katyń in 1940.
After arriving in Warsaw, Karski engaged himself in the resistance movement and he became a messenger for the Polish Underground State. Due to his photographic memory and capacity to speak different languages, he undertook numerous missions for the Polish government-in-exile.
He saw what the Germans were doing to Jews with his own eyes. Disguised, he went into transit camps and the Warsaw ghetto. There, he saw the inhuman treatment of people, many of whom were dying of starvation. He also witnessed numerous executions. These were images that he would remember until the end of his life.
Karski had memorised an abbreviated, 17-minute version of his report – about the structures, the organisation and the functioning of the Underground State as well as the extermination of Jews – by heart, and he presented it to leaders of the United Kingdom and the United States, as well as politicians, bishops, artists, and representatives of the media and the film industry in Hollywood, among others, asking for help for occupied Poland.
Unfortunately, many did not believe Karski’s reports, which were taken as propaganda for the Polish government-in-exile. Karski published his memoirs and report in the form of a book entitled The Story of a Secret State in 1944, which turned out to be a great success, with over over 400 thousand copies published. The book became an instant best-seller and created an outcry among the American public, some of whom were finally learning about the on-going mass-extermination of the Jews and the suffering of the Poles for the first time.