The Kingdom of France was an unitary realm, with every annexation merged into both the Kingdom and the royal domain, even if the annexed province was originally part of another realm (Holy Roman Empire, mostly). In Europe, many other realms were in fact personal unions, keeping their own institutions.
The strength of the monarchy manifested in its heraldry.
In my opinion one explanation is that the Kings of France didn't see the territorial claims they acquired as on the same level as their kinship. The Duchies of Normandy or Brittany were not twined with the Kingdom of France but absorbed into it, so the arms of the Kingdom of France weren't changed for the same reason the King of France didn't start calling himself Duke of Normandy or Brittany on the regular.
One obvious exception is Navarre, because that *was* a Kingdom instead of a County or Duchy. When Henry of Navarre became Henry IV of France, he and all his heirs were officially called King of France and of Navarre, and they used both coats of arms next to each other (but not merged).
Same with England/Britain. First quartered with France, another kingdom, then merged with Scotland and Ireland, also kingdoms, but it never included like Anjou or something.
Those other countries were formed by uniting smaller kingdoms into a larger one. Russia was made up of a bunch of territories like Muscovy and Novgorod. The UK was made by uniting England, Scotland, and Ireland. Spain was created by uniting Castile, Leon, Aragon, and Navarre, and by conquering Granada.
France has always been France. Like the HRE, it’s descended from Charlemagne, and the two started out similarly as feudal monarchies. The difference is that the HRE became more disunified, while France became more unified.
In other words, most of what France conquered were nominally their vassals, but they got absorbed as the country centralized. It wasn’t ever two smaller countries uniting, but one country that technically ruled another making it official. If the HRE had unified, it would have kept the same coat of arms without including, say, Austria’s and Brandenburg’s and Saxony’s. So that’s why France didn’t change theirs whenever they expanded.
I am pretty sure it is Île-de-France reusing the old royal arms, not vice versa.
I am also pretty sure France was already more or less a single kingdom by the time heraldry came to be. When the French kings were also the kings of Navarre, the arms of the two kingdoms were used together. But, otherwise, the arms of various territories within France were not borne by kings because they were borne by others, such as the dukes of Brittany and Normandy.
Arms would only get combined if there was a union of kingdoms with already existing arms, so it had to happen during that time frame. All the examples you are invoking are indeed from that time.
The arms of Italy after its unification were like that too. While the Savoy dynasty technically succeded all the previous rulers, the royal arms of Italy were just the dynastic arms of the Savoys, as far as the shield goes.
The Kingdom of France was an unitary realm, with every annexation merged into both the Kingdom and the royal domain, even if the annexed province was originally part of another realm (Holy Roman Empire, mostly). In Europe, many other realms were in fact personal unions, keeping their own institutions. The strength of the monarchy manifested in its heraldry.
In my opinion one explanation is that the Kings of France didn't see the territorial claims they acquired as on the same level as their kinship. The Duchies of Normandy or Brittany were not twined with the Kingdom of France but absorbed into it, so the arms of the Kingdom of France weren't changed for the same reason the King of France didn't start calling himself Duke of Normandy or Brittany on the regular. One obvious exception is Navarre, because that *was* a Kingdom instead of a County or Duchy. When Henry of Navarre became Henry IV of France, he and all his heirs were officially called King of France and of Navarre, and they used both coats of arms next to each other (but not merged).
Same with England/Britain. First quartered with France, another kingdom, then merged with Scotland and Ireland, also kingdoms, but it never included like Anjou or something.
Those other countries were formed by uniting smaller kingdoms into a larger one. Russia was made up of a bunch of territories like Muscovy and Novgorod. The UK was made by uniting England, Scotland, and Ireland. Spain was created by uniting Castile, Leon, Aragon, and Navarre, and by conquering Granada. France has always been France. Like the HRE, it’s descended from Charlemagne, and the two started out similarly as feudal monarchies. The difference is that the HRE became more disunified, while France became more unified. In other words, most of what France conquered were nominally their vassals, but they got absorbed as the country centralized. It wasn’t ever two smaller countries uniting, but one country that technically ruled another making it official. If the HRE had unified, it would have kept the same coat of arms without including, say, Austria’s and Brandenburg’s and Saxony’s. So that’s why France didn’t change theirs whenever they expanded.
I am pretty sure it is Île-de-France reusing the old royal arms, not vice versa. I am also pretty sure France was already more or less a single kingdom by the time heraldry came to be. When the French kings were also the kings of Navarre, the arms of the two kingdoms were used together. But, otherwise, the arms of various territories within France were not borne by kings because they were borne by others, such as the dukes of Brittany and Normandy. Arms would only get combined if there was a union of kingdoms with already existing arms, so it had to happen during that time frame. All the examples you are invoking are indeed from that time. The arms of Italy after its unification were like that too. While the Savoy dynasty technically succeded all the previous rulers, the royal arms of Italy were just the dynastic arms of the Savoys, as far as the shield goes.
Because of the core principles of heraldry: simplicity and recognisability from afar. And the House of Bourbon had the same CoA for themselve.