It might help to consider the European wars of national consolidation. No one says “oc” to mean “yes” in France because Languedoui conquered Languedoc. Europe was fragmented into city states and riven by perpetual war. It wasn’t about nations, it was about king makers and upstarts and suppressing rebellions. This only slowed slightly with the rise of European nationalism in the 14th century, the century the Black Death destroyed some huge fraction of the population.
If you look at the pattern, Spain was bloodily unified under the Christians, and then Spain and Portugal went on to conquer much of the world with their caravels and cannon. France and England bloodily unified over the next century or two and built their world colonial empire with the Dutch. Germany and Italy bloodily unified in the 19th century and then built a world empire with the Japanese. Those nations were born in blood and iron as Bismark put it, and civilians were not spared. A sword or a musket can kill you just as dead as sarin gas.