The era of Atlantic revolutions and their subsequent independence movements declared that sovereignty lay with the people.
States were inhabited--by people who felt themselves to be citizens of a nation, deeply bound to their fellows by ties of blood, culture, or common experience.
Science-- weakened the hold of religion on some. Migration, to industrial cities or abroad, diminished allegiance to local communities. At the same time, printing and the publishing industry standardized a variety of dialects into a smaller number of European languages, a process that allowed a growing reading public to think of themselves as members of a common linguistic group or nation.
Governments throughout the Western world--claimed now to act on behalf of their nations and deliberately sought to instill national loyalties in their citizens through schools, public rituals, the mass media, and military service.