Use the following trick to get a lot of extra Peasants (more than the campfire limit of 24) for buying whatever kind of forces you need from the Mercenary Post or Barracks. For example, put your Quarries (3 Peasants each) and Oxen to sleep. There will be that many more in your available amount when buying Swordsman or something else. Then just turn them back on when you are done and they will go back to work. This works if you do not want to wait until your Peasants fill up your campfire again, or you just need them immediately.