Thanks for the answers!
Yes, you can take the "Grave Art" as a second choice, but only when you've cleared at least 50% of the Orcish territories – then you can send the hired unit to retire in your castle.
I spent some time in the map editor and reviewed it... I thought about diplomacy and did some calculations – it turns out to be a very useful thing, if you manage to get it right, as they say, "in the groove," and preferably for free. Then there's not much need to fully build up your own castle: neutrals grow like yeast – you just need to pick up "your own" in time and discard the cannon fodder.
However, if you aim to protect the "Club," it's difficult – I had an army strength ratio of 0.3898... diplomacy won't help; I needed to gather 17,500,000 neutrals, which equals 60,000 assassins :eek:
BUT! I'll try playing a third time ;)