While playing, I found a bug that baffled me, and that I don't remember ever finding when I played this game on the Amiga...
I had about a hundred soldiers in my campaign army, went to a tournament, when I came back, my campaign army was empty. No soldiers, no knights (but I still had the catapult, at least). I tried going home, but the home army was empty as well. This happened more than once.
Has anybody else found this bug? What did you do to solve it?

Vassals that you collect from each territory will desert over time. There's not much you can do to stop it. They are replenished as you return home.

It's in the user guide.

I have been discovering this a lot. Im sorry but 18 knights and 80 men disapearing all at the same time has to be a bug.

This is happening to me as well, nearly every game.

+100 soldiers, a couple of knights, a catapult - then next turn, only the catapult. WTF? Never happened in the old Amiga version. Also never had so many regular deserters in the original. Early in the game it can be half my army.

Too frustrating to continue playing.

This may be too late to help, but it looks like this reliably happens if one of your other castles gets captured (that is, not your home castle, but either another knight's home castle that you captured or a castle that you built). The only way to avoid it is to keep the enemy away from all your castles.