
Originally Posted by
torongill
It's the percentage of soldiers of the garrison related to the total population of the province which they're garrisoning. However, there is something else: units with the attribute is_peasant count as half. If you play with the Romans think Hastati, Hastati_Sibeli, Leves. They all are peasant units as far as the game is concerned, meaning that you need two of those in order to get the same garrison level as from one unit of principes. There's also a hard limit on the order bonus you get from the garrison - it's 40%. Any additional units for garrison duty would be superficial once you get the 40% order.