The Danes did not save all. Some where shipped to Germany in Oct 1943 (most survived) & were repatriated by Sweden in 1945, they did save the what would have been the equivalent of 80,000 Jews in France.
German diplomat Georg Ferdinand Duckwitz is credited with tipping off the Danes about the round-up of Jews, but mysteriously all the German patrol boats were undergoing maintenance at the same time - so there were perhaps other Germans helping, unknown to this day https://en.wikipedia.org/wiki/Georg_Ferdinand_Duckwitz
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https://en.wikipedia.org/wiki/Georg_Ferdinand_Duckwitz