A Guide to Preparing for War in Europa Universalis IV

By Admin 16 Jan 2019 0

From some long forgotten vault your diplomat has discovered a document of true and verified authenticity. It proves beyond any doubt that you are the rightful owner of that fantastically valuable province right across the border. But how to claim your birthright? Those villains won't listen to reason, won't give it back, so it’s time to prepare for war!

Paradox's Europa Universalis IV is a game with many facets that you as the player need to try and master. It can be a bit daunting, and not everything in the game presents itself in an obvious manner. This guide comprises of top tips on how to prepare for a war. We will do future guides on actually fighting wars, economic tips & tricks and anything else that we feel may need exploring.

The advice and information presented here is correct as of the 1.28.2 Patch and the Golden Century expansion, which released on Dec 18th, 2018.

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The pre-war checklist

  • The Plan - Check geography, enemy disposition, key war goals.
  • Armies - Increase army maintenance & assign generals.
  • Politics - Check the status of your allies and the enemies.
  • Finance - Build a war chest for army maintenance and replacing troops
  • Enemies - Check military technology parity, relative manpower and army size

The Plan

Never consider going to war in EU4 without first coming to an understanding of what you intend to achieve through the engagement. Build a plan and determine if what you want is possible before you even start warming up your armies on the launchpad.

Sometimes provinces will look extra tasty for just a little military adventurism until you notice that pesky fort which will hold you off for 10 years and allow reinforcements to fall on you like rain or you overextend and your army starves in the field without reinforcements, dying to an inferior force.

EU4 War Plan

  • Switch the map to the Simple Terrain mode and review the target’s territory. This mode gives a clearer indicator of terrain on each province; River boundaries between provinces are defined, blue for a river crossing, black for none. Plan to attack vulnerable forts in flat land where you’ll suffer low attrition and no terrain malus if the enemy attempts to relieve the siege.
  • Switch the map to the Supply map mode and identify places to avoid. Desert or mountainous provinces have low supply limits and an additional supply malus for arid or wintery conditions. If an army's' reinforcement rate is higher than the attrition rate any losses will immediately reinforce back up to maximum. Consequently your army will appear undamaged and it is not obvious you are taking attrition-based losses, although you will see your manpower quickly drain. Try to advance via high high supply limit provinces, like farmlands and grassland. Coastal provinces also have a 50% bonus to supply. At the same time, realize the enemy has the same intention and an easier time on the defense dealing with attrition. If you can force him to march through low supply areas to attack the army you have sieging his fort, his morale and manpower may be depleted in the process. Every bit helps.
  • Identify key battlegrounds: Check for choke-points in mountain passes or along sea crossings. You may be able to use them to box the enemy in, forcing them to attack you in disadvantageous terrain. A special note on horde nations: they receive a 25% bonus to the shock phase when fighting in flat land (grassland, steppe, desert), so avoid fighting them there. They receive 25% malus on difficult terrain.
  • Choose the right war goal and find a good route to the enemy capital. When attacking into enemy territory these the two most important provinces to take. Capturing both will drive up war score and enemy war exhaustion, although you must take any forts near to the war goal in order for you to be able to claim the territory in a peace deal.


The fist on the end of your military arm are your armies, with which you should pummel your enemy aggressively. Power and speed are important aspects, but maneuver can be the decisive difference.

EU4 War Armies

  • Your army should be as close to your Force Limit as manpower and finances allow. Ideally, you will be at maximum Force Limit and fully reinforced with manpower to spare. Recruiting new troops just before a war will drain your manpower by 1k per new regiment, and you'll need that later. Individual armies should have at least 2 cavalry, as they provide vital flanking bonuses in battle. In the first 100 years try to recruit more as cavalry do excellent damage in the shock phase. However, too much cavalry (over 50% for western nations) and you will suffer an 'Insufficient Support' penalty.
  • Armies should also have at least 1 artillery to aid in sieges. You typically won't have this till around 1492 unless you're lucky/smart with technology. As time progresses artillery does more damage in battle, so in the later game aim for a 1:1 ratio of cannon to front line troops.
  • The Army Maintenance slider should be set to 100% and all army morale bars have filled completely. It will automatically jump to 100% upon declaration of war, however if your peacetime maintenance is very low (typically to save money) it may take months for your armies to regain full morale.
  • Your own manpower needs to be sufficient for the war: An evenly matched war requires as close to 100% as possible, although 50% should be enough for fighting a weaker nation. Potential foes will keep track of your manpower and dropping too low can cause an AI nation to attack you because they perceive it as weakness. Plan for failure as well as success; don't commit so much manpower on the move that your borders at home invite someone else to jump on you while you're distracted by the war. Be willing to bail out if need be.
  • Armies should have generals attached with good combat skills where possible. Favor a general with the best shock skill in the first 100 years, as most of the casualties are inflicted in the shock phase, especially with cavalry heavy armies. Later, favor generals with the best fire skill as the fire phase becomes more lethal. Maneuver and Siege are also useful but situational - you can consider swapping in a good siege general only when needed. Also note a higher maneuver skill than the enemy will negate any river crossing penalties.


War may be politics by other means, but keeping an eye on your relationship with nearby countries and others which may be more influential is how you keep your friends close and your enemies closer. A friendly helping hand when you're taking on someone with superior numbers, superior technology, or superior position can make all the difference.

EU4 War Politics

  • Generate a spy network before going to war with your enemy - you will need to assign a diplomat permanently to work on this. This can provide up to +20% siege ability and -10% aggressive expansion impact with that nation. Aggressive Expansion determines how much they’ll hate you and how likely they are to form a post war coalition once you've beaten them.
  • Make sure you have claims on the provinces you wish to capture, as you cannot raise claims during a war. They will reduce the core creation cost, province war score cost and local autonomy by -10% when you take it. Note that you can only lay claim on provinces that directly border your own, with the exception being coastal provinces that share the same sea zone.
  • Check the political situation of your enemy: Is your target already at war and/or are his allies? Check the political tab and try to time your attack when your target is already at war. Review the current war but be careful not to leave it too late and allow peace to break out while you’re still preparing. Right click on the flag of your target (and his allies) from the province view and click the gold star. This will mark them as countries of interest and you will receive a popup to inform you that they are in a war.
  • Check the political situation of your own allies: are your allies ready to support you? Generally, your allies will be more willing to support if:
    • They have been at peace for a while (they have a high manpower and no debts).
    • You have been allied for 10+ years (you gradually gain favours with your allies and can call them into war when you have 10 or more).
    • They border your target or his allies.
  • Consider if your allies can get to you and/or your enemy. If they cannot, will you be able to convince the nations in-between to allow access?


Maybe adding a little jingle to your pocket is why you're going to war in the first place. The wealth of nations is often the driver of militaristic interaction. Having more people under your iron heel is nice and all, but the tax revenue they provide and the trade they give you access to typically justifies the price in blood and treasure to challenge another for their allegiance.

EU4 War Finances

  • Collect a war chest. Save enough money to pay for your army upkeep and to replace lost armies. Remember, you pay for reinforcements with money as well as manpower which can increase your army upkeep considerably. You may also have to resort to mercenaries, in which case you require even deeper pockets. We recommend a couple hundred ducats, but 100 at a minimum should be okay for the average war. Remember you can Raise War Taxes during a war to give you a reduction on Land & Naval Maintenance.
  • Plan for the length of the war. Consider hiring mercenaries to take you beyond your force limit. This is very expensive, however a decisive first battle (overwhelming the enemy with numbers and causing a stack wipe) can dramatically shorten a war. A longer war can easily prove to be more costly than the short term expense of recruiting above your force limit. Hiring mercenaries as a cash-rich and manpower-low nation is a good idea for mid-war as well. Concentrate on hiring infantry, since they take the bulk of the losses in combat (and therefore manpower drain). Recruiting artillery and cavalry normally is a more effective use of your manpower & ducats.
  • Take on loans if necessary. War reparations and future income from captured high development provinces can more than make up for any interest on loans.
  • Check how trade might be affected. If the enemy is likely to gain naval superiority, your trade income could be considerably affected as your light ships are driven from the seas. Consequently you may have less income during a war than you expected. Even if you are successful at sea, your trade fleets may be re-purposed as blockader and be unable to add to your trade power.

The Enemy

No matter how, when, or why you've decided to go to war, the enemy always gets a vote and how things turn out. Whoever you've decided to pick on, make sure that you check them out thoroughly or else you may be deciding to throw hands with an opponent who will provide an unpleasant experience.

EU4 War Enemy

  • Review the target's military technology, which you can find it in by clicking on any of their provinces. It appears in the province overview or from the nation overview in the ledger. Each level gives particular bonuses and you can review your own bonuses and bonuses to come by hovering over the military tech in the technology tab. All other factors being equal, if your opponent is one level above you things will be problematic, two levels will be very hard and three will be all but impossible.
  • Check the target's ideas. While checking the enemy's military technology you can also check their ideas from the diplomatic tab, hovering over the lightbulb will list their current ideas. The more military ideas the more bonuses they will receive during the war. Some of these many be fairly inconsequential but be careful of Offensive, Defensive, Plutocratic and Quality. These provide bonuses to army morale (how long they’ll fight for) or discipline (how much damage they do in combat). These bonuses can tip the balance in a war.
  • Review the targets army status in the ledger. Check the enemy’s manpower, force limit and army size in the military tab of the ledger. If they outnumber you by more than 50% you may want to reconsider the war. A nation with low manpower is an excellent target for attack, they will be forced to replace losses with mercenaries (or not at all) and negative events can fire at 0 manpower. Their war exhaustion and national unrest will already be high which will cause them to sue for peace quicker.
  • Check for revolts. Scan their country for provinces currently occupied by rebels, particularly forts. Even in the fog of war it can give you some indication of the state of your target, you can even spot provinces under siege by the siege animation active on the province. If your target is troubled by rebels you may want to bring your timetable for war forward to take advantage and before the rebels are crushed.


Once you've won or lost, succeeded or failed, come back with your shield or on it, now you have to win the peace.

  • If you've won the war, but generated enough aggressive expansion so that your neighbors declare a coalition of the willing and decide to go to war with you in your weakened state, you're in for a bad time of it. If you've won the war but don't have enough monarch points to core the provinces you've taking control of, you very well may be setting yourself up for shattering civil wars or long-term economic dysfunction.
  • If you've lost the war, any or all of the above could also happen but you need to deal with the repercussions of your enemy's counterclaims, which often involve taking your most prosperous provinces or breaking access to extremely useful trade routes. Not to mention the crippling costs of rebuilding your manpower and your armies among the detritus.

War in EU4 requires a steady hand, a clear eye, and sometimes nerves of steel.

Are you ready? You should be. All that's left to do is to open up that menu and click the button. There's a lot more that could be set on actually fighting wars and strategies for different parts of the world, but the above advice should be generally applicable in all circumstances. Just remember - don't be greedy.

If you have any further comments or advice to give, feel free to post in the comment below!



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