For that character, if they are captain of a formation, their troops get the bonus.
In the case of the player character, it is when you lead a certain unit type in an army. For your companions, it is the topmost companion in any given group. For example:
Group IV companion1
Group IV companion2
Group IV companion3
Group III companion4
In that case, companion1 is horse archer captain and companion4 is cavalry capta
For that character, if they are captain of a formation, their troops get the bonus.
In the case of the player character, it is when you lead a certain unit type in an army. For your companions, it is the topmost companion in any given group. For example:
Group IV companion1
Group IV companion2
Group IV companion3
Group III companion4
In that case, companion1 is horse archer captain and companion4 is cavalry captain.
I dont't beleive it works like this. I think it only counts in army's , at the begiing of a battle when the lord's select which formations they will lead