An estimated 6 million Poles were killed during World War II -- including around 3 million Polish Jews -- as Hitler targeted minorities across Europe.

CNN: Story highlights

The plan appealed to some leading figures, including the Director of Naval Intelligence Admiral John Godfrey, who found Hitler's erratic strategic moves hard to work out.

BBC: NEWS | UK | British 'studied' Hitler's stars

Pope Benedict, who was born in Germany and forced to join the Hitler Youth as a teenager, has spoken out forcefully against the Holocaust on several occasions, including on a visit to the site of the Auschwitz concentration camp.

CNN: Pope on 'high-wire act' tour of Middle East