I was wondering about the inherent risks of death: catching a stray arrow, getting bogged down in melee combat and being slower than a random opponent, etc. It seems like as morale-boosting as it may have been for one's military, it would be excessively risky as death could mean an immediately destabilization of one's government. Or were plans of succession already in place before each battle?
This depends a bit on the culture, but in many cases yes, they did. In this earlier thread, u/Iphikrates writes about Alexander and how this was expected of Ancient Greek leaders in general. You can also read about the same phenomenon with mediaeval kings in answers here by u/Hergrim and here by u/MI13. The Romans were, as u/Iguana_on_a_stick points out in this answer, a bit different in that their leaders tended to stay back and usually come to the front ranks only when the situation was dire. There are also this older thread by u/Bacarruda and two more recent ones (here by u/RustedBarrelKing and here by u/TreeShaun) which take a broader perspective and write some about the end of this expectation (the second of which even mentions the interesting fact that a head of state was killed in combat as recently as last year!). New answers to this question by our users are of course highly appreciated!