Usually the ruler is the default leader of an army raised all within one province, but not always, and there isn't a clear reason as to why. Why is this a problem? Because it screws up the perks in the martial tree. Let's say I have "Living Off the Land" so I can start my army with 300 supply instead of 100. The ONLY way this kicks in from the start is when the ruler is the default leader of the army. I can pause the game, raise an army, and then swap the leader with myself and I do not get the 300 supply perk. I'd have to camp them out for a few years to get that far. When there's no mechanic (that I'm aware of) to ensure your ruler is automatically the leader of the raised army (or heck, another specific character if you'd prefer) then some of those martial perks become largely useless.
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