During the cold war, all of us know that America and the Soviet Union were putting the best scientist of there country in the front to develop weapons of mass destruction.
What most don't know is that not only the Russians but the Americans had embedded spies in them to recover weapon specs and also the science between them. In fact, the cold war is known as the golden-age of espionage.
One of the main reasons for the civil war was the differences with slaves about whether it was illegal or legal to have slaves. This could have been avoided if there was agreement on how slaves should be treated.
D the reign of charlemagne
