How Did Nationalism Cause Ww1

Was nationalism really the cause of WWI? Many people believe that this was the actual cause of WWI, cause of all the pride they teach us to have for our country. All the aggressive press during the years leading up to WWI. Think about school, pep rallies. Just like Nationalism, even if we are the weakest country, we will still have all the pride most in the world for our country. Nationalism in Europe in the 1800’s and early 1900s was the overall cause of the First World War.
Although some of you might say that wasn’t and say it was because of imperialism but in reality it was just nationalism. Think about it because we americans have a lot of pride. all the propaganda all the things the press would publish, it all got to the heads of the americans and made them want to fight in a war that's why so many people actually ended up joining and fighting. They show a good looking woman saying “I WANT YOU” but so they read it and notice the bottom says “for The Navy” then they join because they think good looking woman are in The Navy.
In that case it would be kind of a one on one war, this was the world, why would another country jump in a war for land. when they could watch them lose and take over the country themselves and have more power.
This is why nationalism caused the First World War, and not all the other theories. Generally it was pride something everyone has too much of. If the country just calms down and minded their own business we would all be ok and world peace would