The Enlightenment (or the Age of Reason) was a period when great thinkers were questioning the absolute control of monarchs and calling for democratic principles and the upholding of basic human rights.  Locke, Voltaire, Rousseau, and Montesquieu, among others, were calling for changes in power, authority, governance, and law.  People became more familiar with what their rights were and how those rights were being violated because of these political thinkers.  Revolutions were the result of people having the desire to govern themselves as a distinct nation; the definition of nationalism.  One of the first political revolutions to occur because of Enlightenment thinking was the American Revolution of the late 1700's.  The rights and liberties of American colonists were being compromised by the British government and a revolution occurred because of it, thus establishing the United States of America.  

The French Revolution
Inspired by the success of the American Revolution, French citizens would overthrow the noble, ruling class and establish a democratic government.  The French monarchy under Louis XVI was viewed as oppressive and corrupt and the social structure was rigid, meaning it did not allow for social mobility.  The poor, uneducated class, known as the Third Estate, made up 98% of the population.  The upper classes of nobility and clergy (the First and Second Estates, respectively) only made up a mere 2% of the entire population, as represented in the cartoon.  It is no wonder the people of France rose up in a spirit of nationalism to overthrow the oppressive system and establish a society controlled by themselves.  They wanted to govern themselves as a democracy but maintain their French identity.  This is the essence of nationalistic movements.  

Independence Movements in Latin America
Nationalism would also be the driving force behind the revolutions of Latin America.  The issue behind the episodes of the 19th century involved the shedding of Imperial control from Europe, as was the case in the American Revolution.  Some notable personalities include Simón Bolívar, José de San Martín, and Toussaint L'Ouverture.  Bolívar and de San Martín both raised armies to drive the Spanish out of South America to establish autonomous governments.  L'Ouverture led the revolt in Haiti to cast out French influence.  L'Ouverture's inspiration? the French Revolution.  The Mexican Revolution of the early 20th century was fueled by nationalistic pride but was caused by oppressive Mexican leadership, not imperial rule.  The Cuban Revolution of the mid-20th century was yet another instance where nationalistic feelings sparked conflict.  Cuba's revolutionary figure, Fidel Castro, desired to rid his country of American influence with the aid of the Soviet Union.  This conflict saw some of the most volatile episodes of the Cold War between the US and the Soviets.  The world powers came close to launching nuclear warheads because of Cuban nationalism.  Nationalism is certainly a force to be reckoned with.