khedas you make some excellent points but isn't it true that regardless of papal authority and their feelings on what was de jure and what wasn't that many of the western nations wars occured precisely because certain nations felt that they owned certain territories based on the language spoke by the people there or the fact that it had been owned by them for a period of time. (Normandy obviously and that valley that was annexed between germany and france so many times) Wouldn't that make sense that after 100 years of holding a place the dejure changes not as an actual changing of dejure from the papal perspective but to represent the change in the minds of the people?
Attention, the idea that Kingdoms should be created around the idea of a group of people united by something in common (usually language) is something that started to gain traction after the Thirty Years War (indeed, this is the basis for the whole 'Chambers of Reunion' of Louis XIV that ened up leading to a major war in Europe in the late XVIIth century), gained strong support after the French Revolution and was accepted in the XIXth century, becoming the basis for the unifications of Germany and Italy.
That is, you see, because if a monarch would 'feel' he would be intitled to a territory just because of what the people spoke, he would:
a) be in direct defiance with the will of God, as decreed by His representative on Earth, the Pope;
b) putting into question the whole basis of the system, as he would be implying that a lord might not be the rightful lord of a territory if the people was of a different language/ethnic group. That pretty much threatened the sway of many Kings, and effectively meant that 'your dynasty may not have the right to this title, as you are too foreign'.
Such an idea would be unthinkeable and seen (correctly) as a threat to ALL ruling dynasties, as many ruled 'foreign' lands. He would be declared a heretic, excommunicated and attacked by all his neighbours.
(the first dynasty of Portugal, btw, is called of 'Burgundy', as they were French, from a cadet line of the Capets. The father of the first King could barely speak the language of the land he ruled for 30 years).
In the Middle Ages, about 90% of the wars beteen the Western Kingdoms (holy wars against heathens and infidels were another thing) were caused by one thing, and one thing only: dynastic claims. One family had a claims that they argued THEY were the chosen ones to rule a territory (county, duchy, or the whole Kingdom) and the war revolved around that.
The other causes were:
- peasant revolt for any reason, usually overtaxation or war exhaustion (like Watt Tyler's revolt in England or the Jacqueries in France though those doesn't count as wars in CK2)
- crusades against heretics (like the Albigensian Crusade ordered by the Papacy against the Cathar Heretics in Occitania [southern France] or the ones against the Hussites in Bohemia),
- division between Emperor and Pope about Investiture [a big deal in XIth century HRE];
- Internal attempts to take the throne, either by pretenders or the heir (like the Praguerie, when the 17-year-old Dauphin Louis [the future Louis XI] tried to be declared regent and de facto ruler by his 37-year-old 'old' father Charles with the aid of some major nobles (he was defeated, but would revolt numerous times after that. For that matter, in Portugal between 1279 and 1325 all the prince heirs revolted against their fathers to get the throne early)
- And the one, GREAT exception that is the ONLY time the Will of the People actually mattered: the revolt of the Swiss cantons against the Emperor in 1291. Aided by their mountainous territory, the Swiss held back the armies of the Empire. Still, they had to negotiate a nominal submission as a confederacy later on. The official independence of Switzerland would only occur in 1648, exactly because the end of the Thirty Years War 'broke' the strength of the Empire and let it dependent only of the power of the Austrian Habusburgs.
In all the other conflicts, it was always questions of 'who was owed what': William the Conqueror had no real ties to England, he just claimed Harold had once (was probably coerced into) swearing fealty to him, Philip Augustus wanted back the territories the Plantagenet Kings of England held in France so that his 'vassal' the King of England would not be stronger in France than he was, Edward III started the Hundred Years War based on his claims to the French Throne, and so on. There were some attempts to change this (the rich cities in Flanders tried to kick their French count out, and indeed their support was key in convincing Edward III to start the war with France. It lasted little, and the Count ended up retaking his rightful holdings when the burger leader was assassinated six years later).
In the case of Normandy, the land had been given to be settled by Rollo's normans in the 9th century, and it was not seen as being anything other than French soil. So much so, that it was inherited by one of William's younger sons, who immediately reverted to being a vassal of just France, until it reverted back under the Angevins. And Henry V invaded France in 1415 because he wanted 'his' duchy back, but only because he had claims to it, not because he had any links to the territory (the French had managed to make the English retreat from almost all their French holdings between 1361 and 1384).
Also, note that EVEN TODAY, the rulers of England are also the Dukes of Normandy. That doesn't make Normandy any less French or give Queen Elizabeth II any link to the people there, does it?
In this era, by and large, what the people wanted or were *did not matter* for the nobility. Besides, if that wasn't the case, how could you try to grow through dynastic marriage if you happened to inherit a territory of a different language? People only *felt* they should have land if they had a family tie to it, or if they could get it with the permission of the Pope (this is why the burgundian duke Charles the Bold died trying to attack the Swiss - they were the easiest target for him).
To sum it up, when the People wanted something else that the Pope did not allow, the only exit was to become Heretics and risk the wrath of all Catholics. In fact, you can see here the roots of the Hussite movement as a kind of nationalist movement in Bohemia against German rule. Their only way to express their desire to be a totally free Kingdom was to not accept the Pope nor the Emperor. Thus they became heretics, to the wrath of not just the Germans, but all Catholics - even Joan of Arc wrote to them threatening to stop her campaign against the English and turn against the Hussites, who so insulted God with their heresy...
What I regret is having no chance to recreate the Swiss confederacy in CK2 - there should have been some way for peasants to last long enough in mountains to be able to do that...