When an opposing army brings in the big weapons, your kingdom has no choice but to ante up or fold - and a trained Battle Mage from the Guild of Arcane Combatants if nothing if not a big weapon. But what happens your generals and their generals have a common goal?
"Many strange things may be seen in the Great Swamps, not all real. But I tell you, there was a ship and it was real! Well it was old and all sails torn and had many holes in the hull... but anyway it was hundreds of miles from the Sea! How it came to be there, I can only wonder..."
(If it is not a hallucination, may be inhabited by wererats.)