Hello /r/AskHistorians! I am currently working on a 10th grade research project. We were allowed to research any topic in History, and because of my fascination with Medieval Germany, I choose to look into the reasons why the Holy Roman Empire failed. I have started reading through multiple posts here on /r/AskHistorians, along with multiple pages on the German Wikipedia (Which seems to have more information on the subject matter). I also am about to get started with Benjamin Arnold's "Princes and Territories in Medieval Germany". From what I have read, it would appear that the Holy Roman Empire failed because it lacked a single, long lasting dynasty akin to the Capets in France. This led to the emperor's having to renounce regalia over time, especially by Frederick II (With the Statutum in Favorem Principum).
My question is this: Was the lack of a Hereditary monarchy the main reason why the Empire failed to centralize? Or is there a deeper reason why Germany never centralized in the way, say, France did.
As with the fall of Rome, a lot of reasons are being discussed, but there is no single one that is universally agreed upon to have been decisive.
You mention France as one of the nations that became centralized. But even as late as 15th century, the Dukes of Burgundy were able to ally with England against the valois Kings of France. Marseille did not become part of France until 1482. The border to Spain was not at its present state until the Treaty of the Pyrenees, signed in 1659.
In short, to an observer at the beginning of the Hundred Years War, it would not have been obvious that France was going to become more centralized and the Holy Roman Empire to fragment.
To get back to you question, the lack of a long-ruling dynasty until the Habsburgs has been mentioned as a factor. German literature also stresses the involvement in Italy (Italienpolitik) as a factor. Allegedly, german emperors spent too much time and energy on controlling the papacy and northern italy and too little on the german parts of the empire.
Others point to the fact that Germany was always more fractious than the romanised western part of the frankish empire. The dukes of Saxony and Bavaria like Heinrich der Löwe were never fully controlled by the emperors.
The Holy Roman Empire was also considerably larger than France or England. The larger a country is, the harder it is to control for a central governement, especially if nothing travels faster than a man on horse. Depending on the season, a letter from the emperor in Italy to a vassal in northern germany may have taken a month for one direction.