I believe the reason we only let knights lead armies is explained by the previous combat experience one gains by commanding a smaller regiment during a battle under an experienced commander. Is it truly wise to send someone who had no experience whatsoever at commandeering a small force even to organize and lead a large household army into battle?
It is understandable that some of our younger nobles thirst to lead an army, but they ought to win their spurs first.
I will endeavor to have the BHA with Lothar Steffen and Peter von Kastilien help in defending Zagreb against the ensuing Hungarian assault under the local garrison commander if the city is not taken before they can reach it.

If the Hungarians do indeed take Zagreb before the BHA arrives, I will have it lay siege at once. I believe the two of them should be able to maintain a siege long enough for Jonas von Mahren to arrive.