I am thinking about expanding my RPG fantasy setting into running wargames in it as well. What I am looking for is a game in which several players play the commanders of different units in the same army, each commanding hundreds or a few thousand soldiers.

I want to start with a fairly mundane baseline of medieval combat and then perhaps later gradually add small numbers of special units with unique magic abilities to it. But it should work without any magic elements as well.

I’ve started looking at DBA as a rules system, as it is looking relatively compact and simple to play. Would that be a decent pick for someone completely new and running a campaign for others, or are there other games that might be better recommendations for that purpose?