After all, you don't pay upkeep for dead mercenaries. Mercenaries are high quality troops but their higher upkeep costs make them unattractive as long-term members of the army, but as single-purpose expendable soldiers they are abundant and put up a reasonable fight. Mercenaries should be used sparingly to bolster an army intent on besieging a town or castle or to fill in the roles of a particular unit a faction is lacking in. Faction parties will regularly attack any caravans that belong to their enemies, so it is quite common to find a faction party carrying a few Caravan Guards.
You can also rescue them from parties that have destroyed caravans or bandits who have taken Farmers as prisoners. Troops from the mercenary line are most easily found in taverns, but they can also be acquired by attacking caravans and then convincing the surviving Caravan Guards to join you.
