Nazi monks operating in the Amazon? Secret plans for an air attack on the Panama Canal? Sounds like great Nazi fiction…but it’s a true story (well, at least in part).

In a declassified note to the Assistant Secretary of State, J. Edgar Hoover said, “As of possible interest to you, information has been received from a reliable confidential source that there are rumors current in Brazil as to a German air base, reported to exist in the Rio Negro district of the upper Amazon.”

And here’s more from Felipe Fernandes Cruz at The Appendix:

It was October 1941 and J. Edgar Hoover had just received a strange bit of war intelligence. A secret German air base was being built in the Amazon. This was particularly worrisome, since such an airfield could be used to launch a secret Luftwaffe attack on the strategic Panama Canal. This idea did not come out of the blue. Americans were at the time very concerned about German influence in South America. To monitor potential fascist agents, the Federal Bureau of Investigation collaborated with a Brazilian agency, the Departamento de Ordem Política e Social (Department of Social and Political Order, Brazil’s version of a secret police)…

(See more at The Appendix)