[LDiCesare]

Standard's about the solution to the issue, if it exists.
The problem is that leaders you send to do the fighting (thugs) tend to die, so you have to rely on others leading the troops. There's little way of changing that.

However, I strongly disagree with the proposition that there's never a lack of leaders.
If you manage to trap an army somewhere and assassinate its leader, you may pin it for quite a while by repeatedly killing whatever commander is recruited in that province before he can move (through a combo of assassins, seeking arrows, earth attacks...). This doen't happen very often, but when you can paralyze an army without nearby commanders, you can reap a huge tactical advantage.