I have a candid question then: what did drive the mess of wars in Europe before that? Germany, Switzerland and Italy were a mess of little independent territories fighting each other.
I don't think all of those wars where based on religious grounds.
I am afraid anon1385's text puts the 200-300 year old rise of nationalism in a wrong light.
Before that nationalism, people were not global citizens, quite opposite: their circle of life was even smaller (in a geographic sense). Cities, city-states and small kingdoms. England alone was a patchwork of small quarreling kingdoms ( http://www.thehistoryofenglish.com/pics/heptarchy.gif ).
So the rise of nationalism widened people's perspective, it was a step towards larger geographical areas being united and living in peace within themselves.
So the nationalism was progress. Maybe Germans started to fight wars against the French. But at least now you have countries and larger scale organization, not just a patchwork cities and city-states and local warlords fighting their local neighbours.
You're skipping about 1000 years of history there to make your point. By the time of the rise of nationalism, many parts of Europe had shifted back and forth in control between larger empires for hundreds of years, and it mostly was not a continent of tiny little city states and small kingdoms any longer. The era of the city states started fading quickly after the renaissance, and were in the first place mostly limited to small parts of Europe - most of Europe had seen ongoing consolidation of smaller kingdoms for a millennia or two by the time nationalism became a factor.
Even of the smaller states, many were parts of larger empires for most of their existence, though the control might shift back and forth between empires.
E.g. Germany did not exist as a united country, sure, but the Holy Roman Empire (not to be confused with the Roman Empire) encompassed most of the smaller countries on the territories of present day Germany and at various times part of Italy, Belgium, Netherlands, Austria, France, Switzerland, Poland, Croatia, Slovenia, Czech Republic. Even within the Holy Roman Empire, many of the constituent states were at various times larger than their succeeding present day European states (though there were also many smaller states).
Nationalism in many instances erected substantial new borders in Europe in places where borders meant little to ordinary people before.
> You're skipping about 1000 years of history there to make your point.
This varied by area. Some nation states developed early (England, France, Spain, Portugal, Denmark, Sweden, Switzerland), while other areas was dominated by city states much longer, like Italy and Germany that did not become a nation states before around 1870.
For the most part these countries were monarchies whose territories waxed and waned with the power of their ruling houses, where the idea of a nation with a specific government did not develop much earlier than elsewhere. Their development into nation states in fact largely happened as they contracted into core territories with common cultures and languages and the power of their monarchs was put under increasing challenge.
As for Germany and Italy, while they did not become nation states until late in the game, a large part of that was that they were part of empires and other kingdoms long before.
The Holy Roman Empire (not to be confused with the Roman Empire), the West Roman Empire, the Ostrogothic Kingdom ("heir" to the West Roman Empire, including Italy), the Frankish (Carolingian) Empire, the Bysantine Empire (East Roman Empire); Habsburg Spain; Habsburg Austria; the original Roman Empire.
The period of scattered small autonomous city states was a historical "blip" of not much more than two hundred years due to a temporary political and military vacuum caused by the constant tug of war of various of these larger empires.
The core areas of Germany and Italy had been dominated by organized larger scale governments for the most part of the preceding two millenias (depending on region) before nationalism existed.
There's a gap of a millennium between the 18th century and the link you posted. I was taught William the Conqueror of Normandy came and, well, conquered around 1066 and mark the turning point in England's society by the introduction of the Feudal System. If you we're a mere peasant you tended to stay in your village and work the land for the knights/barons. They might not be interested in nationalism at that point.
