garrisons keep filling with peasants

[kyle_usmc]

So basically I stock my garrisons with high tier units to use as quick reinforcements, but when a war breaks out all my garrisons desert. When I go and look to see why, I find that my garrisons have been filled with 400+ empire peasants(thorios castle, and at rhoetae). I am not sure this is a bug I could see how maybe this is an intentional mechanic, as war would lead to refugees. But it effectively makes garrisoning troops a useless waste of resources.
how to reproduce: garrison troops, wait for a war, peasants will start spawning
no mods installed

 

[ZavodilaSauklus]

I faced the same problem, I had 250 peasants of sturgia in the castle, my castle was in the wilderness in the north, when the war was in the south.