Nationalism seems to have started in the in many different places with many different people during the 19th century. What happened during that century that caused so many people from vastly different places start becoming nationalistic?
Edit: Changed 18th to 19th century. Wasn't thinking straight when writing the question.
Just on a related note, but is there something like "the military school of history" which views such "struggles of society" in a military sense and what do they say about this?
I did study this in first year at university but tragically forgotten it all. I shall try and remember but I think that the starting point would have been disillusionment toward colonialism, empires and metropoles... Any countries that managed to stay independent would have been immensely proud, much like today, to be punching above their weight when you compare the British empires's economic model...
The middle east intrigues me because they were once one/few large countries before they were artificially carved up following world war one. Same goes for India and Pakistan and other select examples. There is nothing more divisive than nationalism towards humanity's shared goals.