Lidia Zamenhof became secretary of the homaranistic Esperanto-Society Concord in Warsaw and often made arrangements for speakers and courses.

As an instructor of the Cseh method of teaching Esperanto she made many promotional trips and taught many courses in various countries.

In December 1938 she had to leave the United States because that country's Immigration Service declined to extend her tourist visitor's visa because of her allegedly illegal "paid labor" of teaching Esperanto.

She was arrested under the charge of having gone to the United States to spread anti-Nazi propaganda,[4] but after a few months, she was released and returned to her home city where she and the rest of her family remained confined.

"[5][6] To another, her explanation was contained in her last known letter: "Do not think of putting yourself in danger; I know that I must die but I feel it is my duty to stay with my people.

"[7] Eventually in the end she was swept up in the mass transport heading to the extermination camp in Treblinka in the course of the Grossaktion Warsaw.

The meeting called attention to Esperantists' efforts to save persecuted Jews during World War II.