Which is why the king didn't reinforce Ramslett during the Zaus invasion.
That was him weakening Ramslett. If Zaus had sent the full 100,000 army, Ramslett would be destroyed, but Zaus would be weakened enough to try and consolidate Ramslett Duchy.
If Zaus didn't and Ramslett repelled the invasion, then Ramslett is weakened enough to not be able to resist the Crown using military over political force.
The king just didn't know that Mob A can craft an airplane and carpet bomb the entire 100k force so that Ramslett's forces was left intact, and that same plane let him sneak into Est Empire, assassinate their Crown Prince and Court Mage, AND rescue the girl.
Again, the king is operating on what he knows, and isn't a genius or an idiot. He's just mid and doesn't know what carpet bombing is.