In my current game, Deorcnysse was without any defense, I walked into with a scout.

Is it what you guys really wanted for this fabled city?

Plus, some turns later, a warg walked in, killed the garrisoned scout and ... immediately razed the city, thanks to the admirable 'AI can instantly raze  taken cities' super-feature.

So seriously, do something about that. I can't imagine you are happy with these things? Deorcnysse should come with a unique building that generate defenders at least.