Lost due to my own stupidity; took three Dragon Utopia, fully built up secondary-conf, but before FB:
1) didn't make a back door in the capital
2) didn't prepare mana (had only 3/140, which is why I put on the red orb, and this was despite Gretchen having two books and magic 16)
3) for a quick return, I dumped the hero into the tavern and returned troops in a chain; it would have been better to surrender the capital and hire a hero in the secondary town and everything would be ok, rather than accepting battle in the castle
4) And of course, the opponent's collections were a complete surprise; there was nothing to be done there without magic(
Well, we learn from our mistakes)
thanks for the game!