Waging war is one of the primary ways to obtain territory.
- Main article: Casus Belli
Wars are fought over Casus Belli. The CB used affects how warscore is calculated and determines the results of the three possible peace treaties:
- Enforce Demands
- White Peace
It is also possible for a war to end inconclusively, which happens when the CB becomes invalid, the defender's liege title changes, the defender becomes unlanded, or (depending on the CB) the attacker dies.
You cannot declare war through the diplomacy menu if you have any levies raised. (Wars from events and decisions, e.g. title revocation and faction wars, are still possible. Non-levy troops do not impose this restriction.)
- See also: Troop types
Sources of troops include:
- Levies, peasants recruited from your demesne and from vassals in times of war. Levies form the bulk of your army.
- Retinues, your private standing army. They cost gold to hire and reinforce, but free when at full strength. Nomadic rulers have their hordes, which function like retinues, but are hired and reinforced using prestige as a currency.
- Mercenaries, hired with gold. They are very expensive but can get you out of a tight spot.
- Holy orders, hired with piety. They only fight religious enemies, and are free of maintenance when defending.
- Event troops, important for tribal characters.
Ships are used to transport troops, and by raiders to store loot when raiding coastal counties. Each ship carries 100 troops. There is no naval combat or blockading in the game. Ship levies are very expensive when raised, costing 0.3 Wealth per ship per month (although pagans and tribals receive a 90% discount). Non-pagans should dismiss ships when they are not immediately needed.
Ships are provided by:
- Shipyards, buildings unlocked with the Shipbuilding technology. In the 867 start, only Germanic pagans, Byzantines and Muslims have this technology. If starting in the Charlemagne bookmark, Norse (the culture) rulers will get en event which gives level 2 shipbuilding tech and shipyards. This happens on/after 793.
- Family palaces of patrician families. Feudal kings may create vassal republics as an early source of ships.
- Naval mercenary bands, after the year 1066, at a very steep cost.
- Conscripted ships: rulers with overseas holdings can conscript 20 merchant ships for 50g.
Fog of war
Fog of war hides troop movements in locations where you do not have immediate vision. The following provide vision in a province and adjacent provinces:
- Troops and ships of your realm (including those of your liege and vassals)
- Holdings in your realm (except those occupied by enemies)
- Occupied enemy holdings
- Allied holdings and troops (if you and your ally are both independent, or share the same liege?)
- Your spymaster (e.g. when sent to Study Technology)
In addition, your Chancellor or Lord Spiritual can provide vision in a single province.
Even with Fog of War, you can see your enemy's total army size in their realm tree. You can sometimes learn the locations of their armies as well, by scanning their vassal and courtier lists for "leading troops in <province>".
Your goal is to raise the warscore to 100%, which will force your opponent to accept your demands. Your opponent may offer to surrender before that, but at 100%, choosing to enforce demands ends the war instantaneously.
If you're on the defensive, or need to bail out of the war, you can also seek White Peace when the war has gone on for a bit and the warscore is still near even.
Warscore can be gained in four ways:
- Winning battles against enemy armies. Defeating the entire enemy army nets 75% warscore.
- Winning sieges and occupying enemy territory. Occupying enemy territory can give up to 120% warscore, with significant bonuses for the enemy's demesne (which tends to be easier to capture due to depleted levies), capital, and the territory contested by the CB. Occupying all enemy holdings gives automatic 100% warscore.
- Controlling the contested title. In some CBs, continually controlling the entire wargoal will add a small amount of ticking warscore each month.
- Holding prisoners. If the leader of a war is captured, warscore becomes 100% in his enemy's favour. Captured close relatives of the war leader also affect the war score.
Warscore gains from victories in battle or from occupying holdings are larger if they're against the war leader as opposed to his allies. Battles have half their usual warscore value in crusades.
Warscore is capped at 99% until you have won a major battle (5% warscore contribution), the war has lasted 3 years, or all enemy territory is occupied. This prevents you from "winning" with quick sieges while your enemy and allies have their forces elsewhere.
- Main article: Combat
It is possible to set game difficulty before start. It ranges from very easy to very hard and morale of both your levies and the AI is affected.
|Army Morale||AI Army Morale||AI Reinforcement Rate|
All holdings have a basic garrison, which increases in size if certain improvements are constructed. Holdings also have a levy which can be raised. When sieging, you will need to have more troops in the county than the defenders have in their garrison plus levy. If the attackers do not have enough men, no progress will ever be made on the siege. Note that a liege can raise his vassals' troops and the vassals' garrisons will show their levy strength as being at full manpower. However, a character who raises the troops from his (or her) own demesne will have those raised levies taken out of the garrison. This means that it is much easier to siege the holdings of a liege who has raised his demesne troops than it is to siege his vassals.
If the attackers do have enough troops, every 12 days a tick will count and progress will be made on the siege. The amount of progress that is made per tick depends on the fortification level of the holding, how severely the attackers outnumber the defenders, the relative siege technology, and whether the attacking army's commander is a Siege Leader. Once a siege reaches 100% progress, it will be occupied by the attacker and warscore will be awarded.
If the army used for a siege is toggled for raiding, a successful siege will not occupy the holding, but sack it instead. However, sieging a sacked holding is usually not difficult (although raiding has to be toggled off, and the army cannot be assigned for raiding again until it returns to friendly territory).
Eventually, the attackers will be able to assault the defending garrison. The amount of time it takes for this option to become available depends on the holding's fortification level and how much the attackers outnumber the defenders. If an assault is ordered, the attackers will start losing large quantities of troops while accelerating the siege progress substantially.
When assaulting, it is recommended to have 10x the number of troops involved in the attack as the defenders have in their garrison. This will minimize the attacker's casualties, as the defenders are overrun and unable to maintain any level of adequate defense. Assaulting is based on the melee value of the unit, making pikemen and heavy infantry rather good at assaults.
Due to the high attrition penalty you suffer in unreformed Pagan lands, Assaulting may be a necessity. Once a Pagan holding is captured in the province, the attrition penalty is gone. Seeking out holdings where levies have been raised makes both sieges and assaults faster, as there are fewer defenders. To speed up conquest in Pagan lands, consider letting an Organizer lead when traveling, and a Holy Warrior leading the assault.
The Home Front
If you are in an offensive war (except Crusades) and raise your vassals' levies, you will gradually incur a stacking opinion penalty, -1 for every 61 days (approximately two months). This penalty will increase as long as your vassals' levies are raised, and will slowly decrease at the same rate it increases. So if you're at war for 4 years, your vassals will end up with a -20 opinion of you which takes 4 years to wear off. If you're a long-reigning ruler with high diplomacy and good vassal relations, this is merely annoying. If you're barely keeping a lid on the dissent as it is, this can be extremely problematic. You can avoid this by calling as few of your vassals' troops as possible or by ending the war as quickly as possible.
Additionally, if your personal levies and retinue get depleted, you could have issues with factions, as they measure the strength of their members against the number of troops you can raise. If half your personal troops are killed off, the power of those factions will increase dramatically, making them more likely to make demands or rebel. This is potentially compounded by more members joining the factions as their opinions of you drop due to the raised levies. Losing many troops is, however, one way to trick a faction - which would normally be too weak - into revolting, thereby allowing you to crush a relatively weak faction and revoke their lands at a mildly convenient time, rather than risking them continuing to gain power and strength and revolting at a truly inconvenient junction. This assumes that you have the wealth to buy mercenaries or that the faction is weak enough to not steamroll assaults through your holdings - you will probably need a bit of time to replenish all those troops you lost, after all.
There are many strategies you can employ to improve how well you do in war.
Before the war
Attack a weakened enemy. If your enemy is deeply unpopular with his vassals, has just lost an offensive war, is dealing with a rebellion, or is fighting a war over a different CB, you can beat him more easily. See also Weakening rival realms.
Weaken the enemy further with raids. You can start raiding with a fully prepared army while they scramble to gather their levies.
Keep your enemy's allies out. Attack while their allies are busy. Get their allies to like you more, so they choose not to join the war. In some cases you can end an alliance by murdering either one of the rulers, or one of the married couple tying the realms together. Or, if you're powerful enough, declare separate simultaneous wars against the two allied realms. If their allies are also your allies, try declaring war on a third party and calling your allies into that war - with them on your side in another war, they can't be called against you by your real target. Note that since patch 2.5, call to arms acceptance is now automatic and forced. However, allies who are already the primary participant in another war are likely to deal with their other war first.
Make sure your vassals and allies are ready.
Invite excellent commanders. By the time you reach king rank you should have at least one organizer , one siege leader , and three excellent flank leaders. Both martial skill and traits matter: see Commander#Strategies.
Gathering your army
Raise only the vassal levies you need to avoid unnecessarily angering your vassals. If you only need the troops of a single vassal to fight a war, only raise those troops. This vassal will now be the only one getting annoyed at you, while the rest will continue to be happy. The other vassals' levies can then be raised later if ever needed. If you're rich enough to support it, you can also consider using only your own levies and retinue, as then no one will be getting annoyed with you. You can also raise vassal levies for the early part of a war, when the largest battles are fought, and dismiss them during the long siege portion of a war.
Raise vassal levies in the best location. You can raise your vassal's "liege levies" in any county belonging to his sub-realm. This is especially powerful if you plan ahead by giving each major vassal a well-placed county (coastal or near your enemies). You can even disband a levy in one place and immediately re-raise it in another.
Consider hiring mercenaries. They can pay for themselves if they allow you to win a defensive war, or allow you to storm castles rather than slowly siege them. If your enemy is weak or you're rich, you could also carry on the war for a while with only mercenaries to let your "Raised Levies" penalty tick down. Hire a mercenary group whose army composition matches your needs: archers for storming castles; heavy cavalry and infantry for winning close battles.
Get allied armies to link with yours. You may have to send some troops over to where your allies are sitting.
Picking your battles
Target part of an enemy's army while it is split up. While you might not be able to defeat the entire enemy army at once, you're likely to be able to defeat half their army, and the rest is then easy to mop up.
Avoid splitting your army up into pieces smaller than the total size of the enemy army. If you do, you risk losing a large part of your army, and being reduced to a position where you can no longer fight back. If you have a really good reason to do so, go ahead, but make sure you keep the rest of your army close. (You can see your enemy's army size in the ledger, or the realm tree accessible from his portrait.)
Outmaneuver your enemy. Organizers and ships do wonders for your ability to control when and where battles are fought. In your home territory, you can also disband levies in order to re-raise them elsewhere.
Take account of terrain. If possible, it's better to be the defender. A close battle is more likely to swing in your favour if you're defending in the mountains or forest and your enemy has to cross a river or strait. Conversely, avoid attacking into defensive terrain if you don't have a large advantage in numbers or quality of troops.
Bait enemies into attacking smaller armies, then send in reinforcements. Immediately once combat has started, send in your larger army. If the enemy can't see your reinforcements due to fog of war, even better: you can have your reinforcements already be on the way by the time the battle begins.
When you are losing
Bait enemies into taking attrition. Using an army smaller than theirs you can continuously pull back, leaving them in a province where their units will slowly die. Only works against large armies or when playing as pagans. Does not work against the attrition-free doomstacks of the Hordes.
When being chased, consider sacrificing a small number of men to let the rest escape. Let a few men remain while the rest go to another province where they can hopefully recover or merge with a larger army. Make sure you leave more than 1/25 of the enemy army, as anything less than this will be destroyed instantly, and as such will not slow the enemy's advance down.
Disband any levies that are doomed. You'll lose half your men if not in friendly territory, but you won't lose warscore. And you can re-raise the levies immediately in another location.
Order early retreat when losing severely. When morale is depleted, your army is forced to retreat to a destination not under your control. Before this happens, you can order early retreat by right-clicking a province to escape to. You can even retreat onto ships in this manner, preventing the enemy from chasing you down. If your army is much stronger at skirmish than melee, you can use this trick to skip the melee portion of battle.
Evade capture in sieges by moving your capital, appointing adult children as commanders, or getting minor children tutored somewhere safe.
If you realize you will lose, try to get white peace.
Check what the enemy's CB is. If a powerful neighbor is pressing a minor CB like a single-county claim, surrendering immediately is a viable option: your realm won't be significantly weakened, your armies will be intact, and they can't do anything else to you for 10 years.
Bankrupt your enemy. His armies will lose a quarter of their morale, and his mercenaries may turn on him or even join you. You can drain your enemy's cash reserves and deny him income by capturing his demesne holdings. (His yearly income and expenses are shown if you hover over his cash balance, and his budget details are visible in his demesne screen.)
Consider what will give you the most warscore. You may be able to get to 100% and enforce demands without certain battles or sieges, or even without really appearing to have the upper hand.
By outmaneuvering or overpowering the enemy you'll be able to win most battles, and eventually the war itself. Some overall tips:
- Construct buildings to increase the size of your army. More details in the guide on construction
- Research relevant tech. It can give you the edge you need. More details in the guide on technology
- Appoint good commanders. Gain good commanders through marriage and invitations
- When hiring mercenaries, go for heavy infantry and cavalry
- Keep your vassals happy
- Strike the right balance between levy law and opinion.
- Don't raise more troops than you need
- Ambush the enemy if possible
- Slow down the enemy's advance by sacrificing units if needed
- Go for the wargoals first
- Go for 100% warscore ASAP
- Divide and conquer
- Utilize the mobility ships give you
- Avoid attacking across rivers and into hills