||Ossietzky worked for the organized German peace movement until 1921 (he resigned from his post as secretary of the German Peace Society because he disagreed with its policy). He became foreign editor of the "Berliner Volkszeitung", a democratic and anti-militaristic newspaper. Later he became editor of "Das Tagebuch" and "Die Weltbühne". Ossietzky criticized the Nazi Party and the disparities of the Weimar Republic, while he actively advocated justice and democratic rights. He warned against anti-Semitism, opposed the death penalty, supported reconciliation with France, and he advocated the acceptance of Germany as an equal member of the League of Nations.
When Hitler became chancellor in 1933 and the Nazi Party became the predominant political power in Germany, Ossietzky was arrested and confined to a concentration camp.