1939 and 1940: https://en.wikipedia.org/wiki/Battle_of_the_Beams https://en.wikipedia.org/wiki/Battle_of_the_Beams Ended when Germany moved the radio gear in p

1939 and 1940: https://en.wikipedia.org/wiki/Battle_of_the_Beams https://en.wikipedia.org/wiki/Battle_of_the_Beams Ended when Germany moved the radio gear in preparation for invading Russia.