What might be some negative results of nationalism from specific history events in the last hundred years?

Negative results of nationalism from specific history events in the last hundred years are:1) Bigotry and intolerance. Human nature being what it is tends to corrupt concepts that should be positive. Isolationism, racism and ethnic conflict are common. 2) Facism. The extreme is always a possibility once the door has been opened. 3) Simplistic thinking and population control through propaganda. Nationalism by its nature tends not to allow deversity of opinions and this results in accusations of disloyalty. As soon as you hear people shout phrases such as "un-American", "un-British" and "un-Australian" etc etc around, its a sign of people hijacking national identity to quell the views of their oponents. 4) Expolitation of the people by their leaders. JFK's already quoted statement can also have a horrendous aspect to it: reducing citizens to mindless drones to be exploited whereby the government does not serve the people, the people serve the government. 5) The creation of false enemies. Either in the form of actual people or in concepts, nationalism tends to create the existence of opposing forces, those who are a threat to the nation. Usually, these are not really a threat at all but are perceived so because they do not conform. Homosexuals, religious groups, ethnic groups, conscientious objectors, foreign powers and new ideas are all frequently portrayed as "wrong" or a threat. Nationalism is a modern political ideology that creates a devotion to one’s culture and is the belief that from acting independent instead of communally will benefit nations which highlight national goals rather than international ones. Nationalism didn’t start till around the 17th, and 18th centuries which is because there was no concept of what a nation was. In the simplest terms, there was a loyalty to the “crown” rather than a loyalty to the country before the French Revolution. There are many varieties of nationalism throughout the world, some of which are beneficial to society and most of which are detrimental. The main type of nationalism that is detrimental to our international society is ethnocentric nationalism, for it causes people to become judgmental and to believe that a certain nation and race is superior over other nations and races. Ethnocentric nationalism is especially dangerous and negative when combined with other types of nationalism such as expansionist nationalism and can even lead to war and genocide. Nationalism began to develop in the 19th century and reached its peak in the 20th century around the time of World War One. (Savich 2003) Also, the earliest mention of nationalism came from a work by Johann Gottfried Herder in 1774 and according to Benedict Anderson, the term “nationalism, only became popularly used in the late 19th century. Two distinct types of nationalism were made by Peter Alter, the first being Risorgimento nationalism and the second, integral nationalism. Nations which seek to establish a state are considered nations with Risorgimento nationalism. Some examples of Risorgimento nationalism in the 19th-century wee Italy, Poland, Serbia, and Greece. (Savich 2003) The opposite of Risorgimento nationalism is integral nationalism which is also known as radical, extreme, right-wing, aggressive-expansionist, and militant nationalism. Negative effects are that it could lead to war, genocide and ultra-nationalism