After capturing the last city, the Sylvan faction is considered defeated. Also, I don't understand why ranged combat is a forbidden skill for all heroes except one.
Ah yes, there's a workaround for the issue where, if no other players' armies remain except for cities, it's considered a defeat because any victory by a relative, other than the king, is counted as a win (since the others are supposedly destroyed). In this case, I don't know what can be done about it (other than making the AI leave the city and leave either Renard or two relatives alive).
Ranged combat is forbidden for everyone except the King and John. Similarly, melee combat is forbidden for everyone except King Renard and Robert (and, of course, Magro, the fully equipped barbarian). It's forbidden because I wanted to test how the game would be fixed if I addressed one of its two biggest problems: the imbalance between melee combat and AI intelligence. Since the latter is beyond reach, I tested the absence (or presence) of melee combat for all sides. The gameplay was much closer to that of Heroes of Might and Magic III, so I decided to leave it as is because it actually made the game even more enjoyable – more diverse, for sure.