@MontyBurns: Lotharingia was almost completely German-speaking until 1918.
Moreover, countries like Flanders were also considered "thiudisc" (Germanic speaking) although a French feud virtually all the time.
Basically, ethnicity and cultural identity was an important notion in the Middle Ages as well, but it didn't have anything to do with politics. Therefore, the power of a monarch has little to do with the cultural differences of his population.
I agree that the claim to Rome, the claim to incorporate a renewal of the Roman Empire, the goal to make the Popes vassals to the Emperors overburdened their power. However, centralization of the HRE failed for many other reasons as well - most importantly the drive for independence and privileges of the princes.
So I firmly believe that for a realistic scenario of centralization, you'll have to have a situation at some point where a majority of the most important princes has a strong motivation to sacrifice a significant share of their power more or less voluntarily, and their successors cannot undo that afterwards.
Moreover, countries like Flanders were also considered "thiudisc" (Germanic speaking) although a French feud virtually all the time.
Basically, ethnicity and cultural identity was an important notion in the Middle Ages as well, but it didn't have anything to do with politics. Therefore, the power of a monarch has little to do with the cultural differences of his population.
I agree that the claim to Rome, the claim to incorporate a renewal of the Roman Empire, the goal to make the Popes vassals to the Emperors overburdened their power. However, centralization of the HRE failed for many other reasons as well - most importantly the drive for independence and privileges of the princes.
So I firmly believe that for a realistic scenario of centralization, you'll have to have a situation at some point where a majority of the most important princes has a strong motivation to sacrifice a significant share of their power more or less voluntarily, and their successors cannot undo that afterwards.