Valdemar Langlet was born in Lerbo, Sweden, a small town south of Stockholm. He graduated from the University of Uppsala and won scholarships to study in Germany, Austria and Switzerland. He worked as an engineer, and as a journalist and editor of several Swedish newspapers, including Svenska Dagbladet. He wrote books about current affairs and about his long trips through Eastern Europe, Russia, and Asia Minor. A gifted linguist, he became a founding member of the Esperanto Club of Uppsala in 1891, only the second Esperanto club in the world. His first wife was Signe Blomberg, a Finnish Esperantist. After her death, he married Nina Borovko, a musician and the daughter of a friend and fellow Esperantist in Russia. In 1931, the couple moved to Budapest, Hungary, where he taught Swedish at the University of Budapest and worked as an officer in the Swedish Legation. During World War II, the couple saved thousands of Jews from the Nazis by providing them with "letters of protection": documents in the name of the Swedish Red Cross. Raoul Wallenberg was inspired by the Langlets to use a similar method when he came to Budapest. The couple were expelled by the Russians after the war and returned to Sweden, where they lived in obscurity. Together, they were named one of the Righteous Among the Nations by the Yad Vashem Holocaust memorial in Israel in 1965. His book about the period, Reign of Terror: The Budapest Memoirs of Valdemar Langlet 1944-1945, was first published in 1946 and reissued in 2013.