[4] Landau's 1936 firing from the Institute for Research into Business Cycles and Prices (together with Kalecki and Marek Breit) was seen as politically motivated and engineered by a senior member of the Polish government, the economist and politician Eugeniusz Kwiatkowski.

[5][6][7] During the German invasion of Poland and the siege of Warsaw, Landau took part in civil defense.

He was able to escape from the ghetto with his family and spent the next couple of years in hiding in the city's Włochy district.

[2] On 29 February 1944, after leaving home, he went missing; in the next days, the Gestapo arrested his family; his daughter committed suicide, and his wife was shot.

[10] From the start of the occupation, Landau kept a diary discussing the effects of the wartime conditions on the Polish people, including the country's Jews.