Flashing red number next to letter symbol

[Jagger]

In the unit stack and message panel to the right of the letter symbol for command, I will often see a flashing red number. Usually it is a 5 or 10 or 15.

What does that number stand for?

[orca]

It means your units will fight at a penalty because you don't have enough command capacity. 5% means they fight at 95% and so on.

[Jagger]

Thanks!

I am still struggling a bit with command.

Say I have a one star general and I have 5 infantry units. Is it better to have the general command 2 units and have the other three grouped separately----or is it better to put all 5 units together under the single general?

Does the army perform worse as a whole, the more units you have over the command limit?

[Pocus]

you will get less combat penalty overall, and you can command the best troops, but you have great chances to fight separately, or have a fraction of your forces not engaged into battle while the rest struggle for his life.
I generally pile my units together, except if the quality is very different between them. Like I have grenadiers and militias, I will leave the militias as the uncommanded rabble they are, and have a general with the Grenadiers and only them. Call me an elitist