So lately I've been educating myself in history on my free time, and I went through some material that sparked thoughts in me that I never had before. Sorry if those things are basic and well-known by this community, but it's a whole new world to me.
So I realized that people across different cultures didn't necessary always identified as said cultures, and that nationalism (as a crystallized form of that self-identification) is a relatively fresh (even if less relevant in 2020) historical concept. And that medieval wars that were fought primarily by hastily conscripted serf levees were not necessarily a Nation vs Nation conflicts, but a Lord vs Lord instead.
So, my question is - at what point in time common folk in European towns and villages realized that they are not just pity serfs from village X which belongs to lord Y, but are in fact a part of much bigger nations?
When England fought France in 100YW, did English levee troops antagonize French people in the same way soldiers antagonized their enemies in 19th-20th century nationalistic wars? Or there was some sort of universal peasant\serf mutual understanding that came before national identity?
If latter is the case and nationality was not important to medieval folk, isn't it a significant "degradation" when compared to ancient world? When free Romans, even not nobles, clearly identified themselves as Roman citizen?
I'd really like to hear someone explain to me when the idea of being a part of a national state visited our minds for the first time, and how it changed through time.
Thanks for your attention, and excuse me for clunky writing - English is not my native language.
Short answer: Only in the 19th century, did modern nationalism come into being; with the variant of ethnic nationalism developing even later. The concept of the nation-state is typically dated to the 16/17th century, at the earliest.
Long answer: Firstly, the ancient world can be very deceptive when it comes to ethnicity and it tends to be overstated.
The Ancient Greeks for example self-identified themselves as Greeks, but had absolutely no problem in waging war on one another; or even in allying themselves with non-Greeks to attack other Greeks. They were perfectly aware that they worshiped (~) the same Gods and spoke (~) the same language, but this did not in the slightest make them less prone to fight and kill each other.
For the Romans, the question who was a Roman was a legal matter; not an ethnic one. A Roman was someone who had Roman citizenship; which was continuously expanded and in (212 CE) extended to all freemen living within the empire. A Roman would have never spoken about the Roman Republic (or Empire) the way a French Revolutionary would have spoken about the French Republic (or Empire). Égalité, yes, but fraternité and liberté ... not so much.
The Migration Period was even more obscure in this sense. The 19th century historians loved to portray these tribes as homogeneous entities; nations on the move as it were. Modern historians have almost completely abandoned this notion. The Germanic tribes, for example, were very fluid concepts and there does not seem to have been any sense of ethnic solidarity among them. Indeed, the very term Germanic is a much later (Post-Renaissance) term for these peoples and there is little evidence of an overarching ethnic identity among them as a whole.
With this in mind, the lack of ethnic identities in the Middle Ages is much more understandable. Medieval identity was a social one, not one based ethnicity: A French knight would have identified himself with an English knight, rather than with a French farmer. The fact that he and the farmer spoke the same language or lived next door, would have been totally immaterial in this regard.
(A French and English peasant, would not have met. Medieval armies that went beyond their immediate surroundings, would have been men-at-arms; not called up serfs. The Hundred Years War for example, was largely fought by semi-professional soldiers, many of whom would become mercenaries following its conclusion.)
Eventually, the Middle Ages would see the reemergence of civic identities; based around cities, which (to some extent) transcended social classes. Nascent national identities however, are closely linked to the emergence of the literate middle class of the Early Modern Period, which were based in the major cities of a particular realm. Among the earliest nations to emerge were the English and the Dutch, followed by the French, Spanish and Portuguese in the 16th century. The English and Dutch had a strong bourgeoisie, were territoriality stable and had high cultural prestige. The same (though with a slightly less prominent middle class) was true for France, Spain and Portugal.
The true catalyst for modern nation-building however, was the French Revolution, which did away with a shared monarchy + religion as the main binding factor and replaced it with the people + an ideology; in its particular case republicanism. Later, during the late 19th century, ethnic components such as language and heritage were added to this mix.
It's important to note though, that these nations are still social constructs. In other words, people didn't suddenly realize that they were part of a larger nation; this larger nation was invented and claimed to include them; which they accepted to various degrees. For example, there were no Germans in any modern sense prior to the 19th century. There was a partly standardized language called German, but there was no real sense of German identity. This came later and did not begin as a grassroots movement among the people, but in the salons of writers and philosophers. The Germans then projected their German-ness back into history, for example talking about the "German unification" in 1871; when historically speaking; it would have been more correct to call the events of that year as the "German formation" and referring to the medieval population of Germany as Germans; even though they (the medieval populace) would not have viewed themselves as such.