How did governments use these new ideas(nationalism and National Identity)on their populations?

The ideas of national identity and nationalism bound people together based on where they lived, where they were from, and what their ethnicity is. Government, local and nationwide, used this sense of similarity to unify people's from certain areas. They often accomplished this by developing an enemy or rival to rally against, for example people who are from the East of a City or a country might be more competitive with people from the West then they would against their fellow Eastsider. Even in modern day politicians use these techniques to get more support from people who identify with one side or another (Ex. Democrats v.s. republicans). During the Enlightenment identifying yourself with a country and claiming another was your enemy could help win you support from common people as distract them from how their own government was being run. This would have been an especially valuable skill to have during this time of Revolution and Reform.

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Smith, Bonnie G., Richard Von Glahn, and Kris E. Lane. Crossroads and Cultures: A History of the World's Peoples. Boston: Bedford/St. Martin's, 2012. Print.