For the factions of other Mount&Blade games, see Factions.
Approximate areas of the five nations in With Fire & Sword.
There are five nations in With Fire & Sword that occupy Eastern Europe. They are constantly at war, trying to take over each others' territory and fiefs. Each faction is distinguished by a different style of army - some have excellent infantry, others excellent musketeers/archers or cavalry, or a combination of these.
Each nation has a monarch and his subjects, as well as a claimant to the throne who waits for someone (the player) to champion their cause. The claimants can be found in random towns. In various taverns, you can ask a traveller for information on their locations at the cost of 30 thalers. Unlike in other games, claimants can be found in taverns of the nation they are the claimant for.
You are not allowed to make your own faction in With Fire & Sword. You can only join a nation (starting out as just a subject) or you can start a rebellion by capturing one of the fiefs of the nation you want to rebel against.
Two minor "factions" should be mentioned here as well: bandits and mercenaries.