But could it be possible to press an icon or button to call to arms every person able in a settlement say 30% to become levy spearment just so you are not easily assaulted at every city if you don't have a large garrison?

I think that would bring a whole new level of assaulting to every settlement, so you could not assault a settlement with 4 or 5 units because the city only had one unit in it.

What do you think?