On his first mission to the Polish Government-in-Exile in Angers, France, in 1940, Karski was tasked with reporting the general situation of Poland under occupation. At this time, he alerted Polish authorities about the grave situation of the Polish Jews.
The Polish Government-in-Exile in Angers, France, entrusted Jan Karski with memorizing the draft structure of the Polish Underground, the division of responsibilities and communications. Emissary Karski transmitted the whole concept to the political leaders in occupied Poland. On the basis on these directives, the first and the most significant resistance movement in wartime Europe took shape.
Karski set off on foot across the Tatra Mountains on a third mission back to Angers in June, 1940, with information gathered from key Underground leaders. The weather was vicious, so he stopped for the night in the Slovakian village of Demjata (black point on the map), where a bribed host turned him in to the Gestapo. Arrested and tortured, Karski attempted suicide in order not to betray secrets. But was saved and transported to a hospital in Nowy Sącz, Poland (green point on the map). Jan Słowikowski, a young physician involved with the resistance, and a group of co-conspirators, organized a daring escape.
In autumn 1942, Karski undertook his last, and most important mission – one that could have saved the remaining Jews of Poland (the red line on the map).