In WW2, Britain was initially overwhelmed by the Nazi Germany aggression. They did have a strong military and intelligence know-how, but that was not enough. T

In WW2, Britain was initially overwhelmed by the Nazi Germany aggression. They did have a strong military and intelligence know-how, but that was not enough. That is when they decided to request the help of the US. The US assimilated much of Britain's military technology via the Tizard mission. https://en.wikipedia.org/wiki/Tizard_Mission https://en.wikipedia.org/wiki/Tizard_Mission From that close collaboration, the US also assimilated much of the British intelligence know-how and created institutions that mirrored the goals of British intelligence institutions. The predecessor of the CIA was meant to be an equivalent of the British MI6. That is to me the true start of the CIA, NSA, etc.