Hitler's surprising obsession
One of the links given is to this blog. Note also:
Speech at the US Holocaust Memorial Museum about Esperanto
I participated in this event, sharing my knowledge with the Holocaust Museum in Washington.
Review of the book La Danĝera Lingvo
This is Don Harlow's review, in English, of "The Dangerous Language," the most thorough documentation of fascist and Stalinist persecution of the Esperanto movement.
New to me though is the reference to Valdemar Langlet, a Swedish Esperantist who saved many Jews from the Nazis.
Charlie Chaplin used Esperanto as the language of the Jewish ghetto in his landmark 1940 film The Great Dictator. I have known about this for decades but never attempted to research what motivated Chaplin. The blogger links this to Nazi persecution of Esperantists. Chaplin could have known about the Nazis' opposition to Esperanto and Esperanto's internationalism which Chaplin would have endorsed.
The blogger does not explain the poster reproduced on his post, and above. It is one of the anti-fascist posters in Esperanto produced during the Spanish Civil War.