Formations are the groups of porcos which units are made into. Furthermore formations are divided into troops of a particular unit with a set cap on how many individual units can be in one troop. Usually this cap is 20, though for some units such as rock throwers and javelins it is 10 or 15. On the battlefield, troops are the ones fighting as one cohesive entity so its important for a troop to be at its cap instead of having lots of troops holding small amounts of units since this affects the troops mass. Every formation has its own home city which supports it with its population by providing the formation cap for it and can therefore only recruit from that home city unless it is changed. If a city cannot support all the units in a formation designated to that city its growth of active population will be impacted. The limit on how many units in active formations that a city supports is its total active population / 2. There is no limit to how many troops or units that can be in a single formation.
- Militia - Does not count to formation capacity and its units are directly supported from a city's active population, meaning that any losses impact the city's actual population. Militias also impact loyalty significantly and are not able to move. Costs no state power to maintain.
- Army - The most basic formation type, used for exploring, warfare, hunting, and garrison when militias are unsustainable to maintain. Costs 5 state power to maintain.
- Settlers - Comprised of civilian units, porcos and sows. Cannot explore undiscovered tiles and are used to found new cities (?unsure please fix). Costs no state power to maintain.
- National Army - All the traits of an army however it can be commanded by anyone in your nation that is a field marshal (by default, only the leader). National armies cannot explore undiscovered tiles. Additionally, they cannot be subject to "events" while moving. Thus, the formation cannot be lost at sea, ideal for fishing or moving between continents. Costs 3 state power to maintain.
- Nomads - Cannot be created by a player and is created only by NPC forces. All animals, nomads, and barbarians are nomads. Nomads are not bound to cities and can be of any size. Unknown how much state power to maintain.
Strategy / Tips
It is always good to create an army in the very beginning of the game that nears the formation cap of the city. Although population is scarce in early times, this benefits in the long-run since workers are much more valuable as the game progresses. Having an active army that you occasionally pull 1-3 workers into every day is much more sustainable than suddenly recruiting an army of a couple dozen units which may put your economy into shock.