How did the French Revolution lead to nationalism?

In Europe, during the mid-1700's, most regions of land were under the rule, leadership, and protection of a king.  The people were divided into classes - the aristocracy, the clergy, and the peasants.  As the people began to identify themselves more as members of a region, or nation, they became dissatisfied with this method of classifying themselves.

In 1789, the unrest with this servitude to a king vs. recognition as equals within a nation served to be the roots that brought about the French Revolution and a state of nationalism.

This idea soon spread across Europe.  Each area embraced its own nationality. Soon a series of separate and distinct nations slowly emerged from the proliferation of kingdoms.  Though there was still a "separation" of classes, all were now united under devotion and allegiance to their own, distinct nationality.