Taxes collected from the province are placed into the garrison's inventory, and so can be used to pay the garrison's maintenance costs. For example, a garrison of ten soldiers would require 20 gold per month to support. Since a garrison helps keep a province civilized and lawful, grateful peasants in the province contribute goods and services toward supporting the garrison. For every 20 peasants in a province, the cost of maintenance for the province garrison is reduced by 1 gold piece. The maximum reduction is 50 gold pieces.
Stacks can defend a garrison just as any other stack.