Not required to advance to Modern Times.
As far back as 500 BC, the Chinese military strategist Sun Tzu stressed the importance of the gathering of covert information about one's enemy. Although every world government has strict laws and penalties to deal with spies, covert intelligence is an important political, technological, and military commodity. During times of war, covert operatives provide important information about enemy troop movements and weapons technology. Spies may also be called upon to perform acts of sabotage in order to delay or divert the enemy. In peacetime, organizations such as the CIA use operatives to keep track of potential political situations abroad. Spying is not limited to politics and war; industrial spies are often used to gain information about rival companies.