I'm actually interested in why the tax is so high in the first place.
From what we know:
1) The kingdom went through a resign change(or something) recently and alot of voodoo magicians were killed.
2) The king used to be kind.
3) The king is desperately taxing the citizens and should know the citizens are having trouble paying.
4) The soldiers are barley making ends meet, although that is better than the villagers.
5) The villagers and soldiers were not on the brink of starvation.
6) We have heard no news of forced conscription, recruitment offers, ect.
7) The soldiers were friendly to merchants but wary of suspicious individuals.
So it is not farming or crop related as it would likely result in famine/food shortage. The military is not being paid excessively or seemingly expanding as the base soldier is paid the minimum and we havn't heard any recruitment offers.
Either this is a king that has gone senile and lost his mind, this is a result of corruption of a greedy noble or faction of nobles, or the king is being used as some sort of puppet and is not being properly informed of his kingdom and it's standing.
Prediction: The result will be that the MC wins the battles and resolves whatever issue that is causing it. An alliance/ treaty may be made as a result. He will gain fame, military prowess, and definitely honorary peerage. The griffin may step in at the last moment and be deciding factor when things look grim.