Sigrid Undset was a member of the association of Norwegian authors from 1907. She was the head of the Norwegian Authors´ Union during the years 1933-1935 and the chair of the Union from 1936-40. Knut Hamsun protested against the decision to award the Nobel peace prize to the German Carl von Ossietzky, who was under detention in a Nazi concentration camp. With Sigrid Undset in the lead the Norwegian Authors union went against Knut Hamsun’s protest.
Sigrid Undset voiced her opinion in strong terms against Nazism during the 30s. As a consequence her writings were banned in Germany.
She had a good income at times. Many people turned to her with a plea for help. She was a generous donor to the poor and needy.
When the winter war (1939-40) took place in Finland, she took three Finnish children into her care. She gave her Nobel medal to raise income for Finnlandshjelpen (foreign support of Finland during the Winter War).
During her exile in the USA in 1940-45, Sigrid Undset worked as an information soldier for Norway and the allies. She continued her tireless fight against Nazism and she engaged herself on behalf of the Jews.
In 1947 Sigrid Undset was awarded the The Grand Cross of the Royal Norwegian Order of St. Olav “for distinguished literary works and for services rendered to the country”.