Creyeditor wrote: ↑12 Jun 2021 10:56
I was suspecting that the regime is in some way independent of the timing of succession.
Not sure what you mean, there?
I think I like the idea of "stated preference of the preceding leader"
This is what leaders throughout history have attempted to establish - not only does it greatly increase stability, it also greatly enhances the power of the leader, since everyone has to suck up to them if they want a promotion.
But it does have its own weaknesses, particulaly if succession is on the death of the leader. If they're no longer around to enforce their will, their preference may not be respected. It may also not be clear who the preferred successor actually is - a famous example is Edward the Confessor, where both Harold Godwinson (Harold II) and William the Bastard (William I) claimed to be Edward's chosen successor (leading to the Battle of Hastings). It also tends to put a giant bullseye on the back of the chosen successor, since everyone knows that if they kill them quickly, they might be chosen themselves.
One way around this is the custom of executing all candidates other than the chosen one (as the Ottomans did, for example). This, however, creates an even worse potential instability: what if the chosen one dies, or falls out of favour, before succeeding? Even when other candidates survive, this can cause a crisis: if everyone knows who the chosen heir is, nobody else positions themselves to take over, so when there is no longer an heir, chaos can reign. [a famous example: the Wars of the Roses. The core problem was that when the Black Prince died a year before his father, it left his son, a ten-year-old, as heir; but this was exacerbated by the fact that the lack of time between the two deaths led to a lack of certainty over who should act as regent, particularly between the young king's three warrior uncles, Lancaster (who happened to be in the country at the right time), York and Gloucester.]
It can be helpful to give power to the successor in advance, to prevent any complaints later. This, of course, means the successor can try to accelerate the process. For a while, English kings used to nominate their chosen successor as co-ruler (as Romans frequently did), but this didn't last long. Particularly famous was the attempt by Henry II's sons to replace him.
One solution found in some places (most famously Japan) was to clearly demarcate the relative roles of the 'old' and 'young' rulers: in Japan, the old emperor would 'retire' early in their reign, and give administrative power to a successor, while continuing to exercise considerable influence and ritual authority - essentially, a CEO/Chairman relationship.
but I will couple it with a meritocracy-like system for the short-list were only high-ranking native members of the military are eligible.
Limiting the shortlist in this way is common, yes. Historically it was common to have a 'prince of the blood' system, in which only people in specific relations to the previous monarch were eligible to become the next monarch, thus limiting the number of potential candidates, and hence the possibility of war. A non-hereditary example is the Papacy - although theoretically any Christian man can become pope, in practice by long convention the pope is elected from the college of cardinals.