I skipped around to chapters involving the kingdom awhile back. So my memory of the exact happenings aren't great. And I can't really write it in an amusing or justifying way. I'd recommend doing what I did back then yourself rather than reading my unamusing summary lacking all sorts of details.
In the novel, kingdom chapters are told from the viewpoint of various members in it. This is from the various chivalric order leaders, the king, a beastman or 2, and a high position mage. If I recall anyway.
I remember 5th chivalric order's mages are basically burned to death and the rest get hit by hard retribution. King slaughters the messenger that delivers news of their utter defeat. Other chivalric order leaders are shocked.
Kingdom gets paranoid because all their actions keep getting thwarted and hurled back at them with things similar to what you see at the end of this chapter. Their powerful relics/weaponry are shown breaking or being drained of power. As they visit the forest, they only encounter beasts "they sent" to help corrupt the forest or something, and none of the native forest species they want to be weakening or dead. The beastmen being abused or about to be sacrificed are freed, while the mage slavers responsible are struck or combust.
King is shown to be old, and is extending his life through a bunch of sacrifices and draining forest of energy. He is doing all this because 3 god candidates tried to boost their favorability in becoming full time gods, and gave him an "oracle" to do what he is doing for power and world rule. Enslaved all beastmen and forced them to breed for sacrifices. Shown to have enslaved his daughters and wifes, and will murder without hesitation when things go wrong. And of course the murder keeps happening and he himself descends into visible madness + delusion. Eventually gets permanently hurt/dismembered, despite his kingdom's power supposedly allowing easy healing.
Beastmen chapters are mainly the kids perspectives, and essentially their thoughts and actions as they regain their free will and senses. I think there was one where beastmen were to be used as combat units in attack on forest, which failed because they got freed of enslavement.
High position mage is shown increasingly regretting his actions but not stopping. Despite also recognizing everything that worked in the past no longer does. Also extending life similarly to king.
A couple of the order captains see the kingdom degrading and collapsing further, and plan a rebellion as they recognize the madness. Also fearing MC's spells.
Ends without much conflict because kingdom's power source is eventually outright broken from MC casting more and more curse countermeasures over time and purifying the forest. While the kingdom's forces keep trying to do actions that trigger said countermeasures. Power source breaking causes the king and several higher position mages to age rapidly and die, as their life extension is tied to that power source. The rebellion started during (or because of) another wave of MC's retribution spells, but the rebellion captains don't get hurt by it that time. All while MC didn't know, and the Kingdom didn't know of MC.
MC basically finds out about the kingdom while just trying to leave the forest. Also learns of the fate of the 3 god candidates, which I think is to be removed from candidacy and forced to live in the world they created? Regardless, MC is asked to take up a godlike position from another god explaining the situation. I forget if he does or doesn't. There's another arc involving a completely different nation investigating the forest that I didn't read or skim into.
Just remembered, long before the rebellion, MC does end up caring for a couple of the escaped beastmen children, and I know the young boy and girl slowly warm up to MC and the various animals. Not to mention golems, which they were scared of initially. I believe the kids are the reason for slave drivers being targeted, since MC found out about it. It's also revealed that many of the freed slaves are alive and well enough in and out of the forest elsewhere, which I think is part of the reason for the arc with the different nation.