The Orc invasion saw the nations of the Northern Continent not providing full assistance, and now, as fortunes have shifted, they'd likely struggle to make a decision to deploy their full forces at once.
Beyond a vengeful mindset, there is also the issue of strength. In the previous wars, the Alpha Kingdom had been wounded in its vitality, and only now has it slightly recovered.
To ask them to launch a distant campaign at this moment would indeed be quite challenging. We can't have too great expectations for the situation in the Northern Continent.
"Inform the Franterune Kingdom, if they can't hold back the Orc onslaught, they should fortify the ports and wait for reinforcements."
He didn't even mention Moxi Duchy. Clearly, that half-capable kingdom was completely overlooked by Charles III.
Even though Moxi Duchy didn't perform badly during the Orc invasion, that was under the premise of having allies' help.