EU4 - Development Diary - 6th of August 2019

  • We have updated our Community Code of Conduct. Please read through the new rules for the forum that are an integral part of Paradox Interactive’s User Agreement.
Showing developer posts only. Show all posts in this thread.


Field Marshal
112 Badges
Feb 4, 2011
  • Ship Simulator Extremes
  • Imperator: Rome Deluxe Edition
  • Imperator: Rome
  • Hearts of Iron IV: By Blood Alone
Good day and welcome to another Development Diary for EU4's upcoming European Update + Expansion. After enjoying a plethora of maps, missions and other content work from our esteemed content designers, I'm here to turn our attention towards the mechanical changes and additions we can look forward to in said European update.

We're going to start with Mercenaries. Not too long ago, I penned a dev diary outlining our ambitions with mercenaries

I'll take this moment to draw attention to the fact that the UI and numbers are far from final

6th Aud DD macro.jpg

In the upcoming Euro update, the old method of recruiting mercenary units one by one in individual provinces is replaced by the action of hiring Mercenary Companies. Mercenary Companies are complete armies of pure mercenaries, as such will not consume from your manpower pool. They can be recruited in any of your core provinces, where they spawn at full strength, but with low morale.

Mercenary Companies come in two flavours: Local Mercenaries and Foreign Mercenaries.

All nations have three bands of local mercenaries available for recruitment, ranging in size from small to large, capped at a minimum of 2 units and a maximum of 40, depending on the development of your nation. Other than the fact that all nations will have local mercenaries available for hire, there is nothing special about them.

6th Aud DD company available.jpg

Things get a little more interesting with foreign mercenaries. Across the world, there will be foreign mercenary companies, tied to a province of origin; the Free Swiss Guard from Bern, the Flemish Company from Vlaanderen, the Raiders from Navajo etc. These companies come with their own General who is loyal to that unit and that unit only. They also can have different costs and modifiers on the unit, depending on which company you hire from. These companies can spawn and despawn over the course of the grand campaign, but no matter how much you want any particular mercenary company, you can only recruit Mercenary Companies within your trade range. So while you may feel confident invading a colonial Portugal, know that they may well have a far larger pool of Mercenary Companies to draw upon.

6th Aud DD Frisians.jpg

So let's take a closer look at the mercenary units themselves. They are typically more expensive than your standard nation's armies, although those costs compared to the current 1.28 mercenaries are likely to be reduced. This is largely due to how Mercenaries will no longer have unlimited manpower, able to feed themselves with coins and bandage wounds with solid gold. No, from the upcoming European update and going forward, Mercenaries will have their own local manpower, unique for their army

6th Aud DD local manpower.jpg

Not to belabour the point, but UI and numbers shown and discussed here are far from final

Once you hire, for example, this Cossack Host, they will replenish any lost souls from their own unique manpower pool until, eventually, they will be completely exhausted and no longer able fight at full strength, leaving them liable to be wiped out in battle. Our intention here is for mercenary companies to be the muscle you flex in times of war and conflict, rather than the go-to permanent standing army for all nations. To this effect:

Make mercenaries always stay at 100% maintenance

We added this and are quite happy with the results. If a nation chooses to rely heavily or exclusively on mercenaries at all times, they will certainly be footing the bill for them.

As for when you terminate your deal with any Mercenary Company, they will leave your nation and your command like all other units, but will not be available to hire by your nation for 10 years. If, in time of great war, you may find yourself at a disadvantage if you have exhausted your access of mercenaries against a foe who has many other companies at their disposal.

You may notice that the Local Manpower for a mercenary army replaces certain actions in the UI. While mercenary regiments can still be consolidated, they fight as a single unit under their leader. They will not accept being lead by another leader or army and cannot be split, nor merged with another. In the event that their leader dies, they shall elect a new leader from within.

6th Aud DD dead leader.jpg

In playtesting, this has lead to it feeling rather chunky, when manoeuvring multiple stacks which cannot be merged together, as they can have different arrival times and movement paths. We are looking into a better way to manage such stacks of armies, and as inconsistent arrival times has been a bugbear for some time, it seems a fitting moment to address it.

Some other points about Mercenaries which warrant bringing up here:
  • Hiring a Mercenary Company won't prevent another nation from hiring from that company too. We didn't want to create a situation where the player who clicks fastest gets those juicy Swiss mercs.
  • Mercenaries will use your nation's military stats, then apply any of their own modifiers on top of that. We did not want to echo the situation in EU3, where mercenaries would end up clearly spending all your money on booze because they were too drunk to fight well.
  • Mercenaries will be hired through the macro builder rather than through the provinces. This should help reduce click fatigue, but also necessitates some work on the Macro Builder, which we'll address in a future DD.
  • With Mercenaries no longer being a bottomless source of manpower, base manpower is likely to increase for all nations, likely by increasing the base amount development gives and/or boosting the value of manpower buildings.
  • Mercenaries are to use unit models fitting for their origin.
  • All changes above are going to be part of the free update.

This is a major change to system that has been largely untouched since EU3, and it won't be until 2020 that this update hits the shelves. The system is likely to get some refinement based on playtesting and feedback. Early results show a lot more involvement with Mercenary Companies, especially in multiplayer. Hearing "Oh bollocks he hired the Swiss" down the microphone certainly evokes much glee, but we shall continue refining the system. We shall be back with more about Mercenaries, as well as the content that goes hand in hand with the system, as development continues.

As ever, comments and feedback are welcome in the thread. Next week we'll be tackling another large change coming in the European Update.
Last edited:
  • 1Like


HoI4 Tech Lead
Paradox Staff
2 Badges
May 11, 2018
  • Battle for Bosporus
Will the composition of available mercenaries change over the ages? As in, less/no cavalry in the later stages of the game.
Each foreign mercenary company will have its own infantry/cavalry/artillery ratio. Some will favor infantry, some will rely on more cavalry than average, others will bring a lot of artillery. They also come with own set of military modifiers on top of the hiring's country, which will usually work in favour of their preferred composition.


HoI4 Tech Lead
Paradox Staff
2 Badges
May 11, 2018
  • Battle for Bosporus
Nice. But weird to allow nations to hire the same company.

Unrelated maybe but can we get some new info on the soon small patch for the introduction of the 64-bit system? Can you please add a quick modification to the AI to be more willing to convert their provinces eventhough it costs them some cash.
We tend to avoid "quick" modifications to the AI for the simple reason that rarely are. This is not the kind of changes we like to rush in ;).

Caligula Caesar

Stellaris Technical Scripter
Paradox Staff
63 Badges
Nov 1, 2014
  • Europa Universalis III Complete
  • Europa Universalis IV: Res Publica
  • Europa Universalis IV: Third Rome
  • Heir to the Throne
  • Europa Universalis IV: Call to arms event
  • Europa Universalis IV: Wealth of Nations
  • Europa Universalis IV: Conquest of Paradise
  • Europa Universalis IV: Art of War
  • Divine Wind
  • Europa Universalis III
  • Europa Universalis IV: Pre-order
  • Hearts of Iron IV: Cadet
  • Stellaris: Federations
  • Crusader Kings II: Monks and Mystics
  • Hearts of Iron IV: Together for Victory
  • Stellaris: Leviathans Story Pack
  • Stellaris: Digital Anniversary Edition
  • Europa Universalis IV: Rights of Man
  • Europa Universalis IV: Mandate of Heaven
  • Crusader Kings II: Reapers Due
  • Europa Universalis IV: Common Sense
  • Hearts of Iron IV: Death or Dishonor
  • Crusader Kings II: Holy Fury
  • Europa Universalis IV: Cradle of Civilization
  • Europa Universalis IV: Dharma
  • Hearts of Iron IV: Expansion Pass
  • Stellaris: Humanoids Species Pack
  • Stellaris: Apocalypse
  • Europa Universalis IV: Rule Britannia
  • Cities: Skylines - Parklife
  • Stellaris: Distant Stars
  • Crusader Kings III: Royal Edition
  • Crusader Kings III
  • Stellaris: Lithoids
  • Age of Wonders: Planetfall
  • Europa Universalis IV: Golden Century
  • Europa Universalis IV
  • Europa Universalis III Complete
  • Europa Universalis III Complete
  • Cities: Skylines
  • Europa Universalis IV: El Dorado
  • Crusader Kings II: Way of Life
  • Imperator: Rome Deluxe Edition
  • Crusader Kings II: Horse Lords
  • Europa Universalis IV: Cossacks
  • Crusader Kings II: Conclave
  • Stellaris
  • Crusader Kings II: Sword of Islam
  • Crusader Kings II: The Republic
  • Crusader Kings II: Rajas of India
(3) No restrictions on the hire of mercenaries based on culture religion, relationships etc.

Actually, each mercenary company has a trigger field where we can put conditions in for who can recruit them. So certain ones are only available for e.g. Christian countries, and others need your capital to be in the same region. So expanding into a new region will usually mean you get more mercenaries available, but it doesn't mean that you will now be able to access all of the mercenaries that are present in that region as some will be reserved for the locals.


HoI4 Tech Lead
Paradox Staff
2 Badges
May 11, 2018
  • Battle for Bosporus
is there a way for them to not get dogpiled the moment they lose a war?
Well one way could be to seek peace _before_ they reach a point where they are so utterly crushed that it would take years before they can offer some resistance to any neighbour not under a truce ;).


Field Marshal
112 Badges
Feb 4, 2011
  • Ship Simulator Extremes
  • Imperator: Rome Deluxe Edition
  • Imperator: Rome
  • Hearts of Iron IV: By Blood Alone
This is like 80% of what I expected

Then I'd be curious to know what the other 20% was.

Changes sound good, but how will this affect the RNW nations and custom nations?

They're not in at the moment, but we highly desire having Random Mercenary Companies in the new world for RNW games.

Will you address the other source(s?) of inifinite manpower? Manchu banners for example. Maybe let them work with a small manpower pool like the mercenaries, and let them gain some manpower from looting?

Unlimited Manchu Banners will feel considerably less unlimited.

1. Does 'own modifiers' refer to the company-specific modifers, or to ideas like 'Mercenary Discipline +5%'?
2. What happens to national ideas with ideas specific to mercs, like the aforementioned 'Mercenary Discipline +5%', if companies also use the nation's military stats?

We're taking a broad look at said modifiers, and they will likely change by release. There will still be mercenary-only modifiers, but the likes of "available mercenaries +25%" from admin ideas are sure to change.

Anyways, as a player who doesn't use mercs much, I hope this new system gives it that added touch of flavor that makes using mercs fun/enjoyable. I'm also hoping this is a free feature... I'm sure there's plenty of other mechanics like [redacted] and [redacted] to go into the [redacted] dlc.

Mercenary Companies will be part of the free European Update coming next year.

How will mercenary armies actually look, composition-wise? Would be a shame if some of them weren't worth paying for due factors like too much cavalry and stuff. Is there some kind of formula or entirely random? Maybe it depends on where you buy them too?

The composition, among other things, is scripted for the companies. as an example:

# Mesopotamian Mamluks
merc_mesopotamian_mamluks = {
    regiments_per_development = 0.075
    cavalry_weight = 0.4
    artillery_weight = 0.2
    home_province = 410
    trigger = {
        religion_group = muslim
        capital_scope = {
            region = mashriq_region
    modifier = {
        cavalry_power = 0.1
        cavalry_shock = 0.1

As for the compositions, as well as the costs, these numbers are far from final.

Would be nice, if you couldn't attack countries with their one companies.

Will there be new events? Like if you hire Swiss company and start the war against the Swiss will they rebel?

There will be events tied to Mercenary Companies

6th Aud DD the trouble with Scotland.jpg

Whats more, does that mean that we will have a real Rework of colonial nations (and colonization)?

Colonisation rework is not part of the scope for the upcoming European Update.

Does the Merchant thing means that we have to have assigned Merchant to a Company, or to a Trade Node they reside in?

Trade range will suffice for accessing Mercenary Companies, no need to actually assign merchants.

1. How did you come up with 10 years? Randomly or through testing?

All first implementations have a reasonable estimation for best value, but they seldom survive first contact with actual playtesting. The values shown in this dev diary should not be taken as final, and will be balanced out in the sizeable journey towards release. We may find that a 10-year delay on re-hiring the same merc company works best, or that it's wildly too short or too long, and will balance accordingly.

Strategic planning?
What's strategic about it?
If it's about SP then the player will always hire the mercenary company before AI, because he is simply smarter
If it's about MP, then the player who has a lot of money or just first made the decision to declare a war will hire the mercs first.
There's 0 strategy behind it

This is largely the thought behind not making merc companies simply be first come first served.

How do you get the mercenary troop?
Does they spawn in your country or does they will walk thu the country(ies) to get in?

Can you hire mercenaries from your enemy /rival?

My opinion on these 2 questions are, I would personally prefer having the mercenaries walking to get to your border in a uncontrolled way and peacefully (meaning they can't get ambushed). And I think that you should not be able to hire mercenary from your enemies, rival and historical rival as well.

I am looking forward an answer from you guys.

Mercenary Companies can be hired so long as their province of origin is within your trade range, even if that province is owned by your bitter war rival, and they will be spawned in any of your core provinces. We briefly considered having them spawn exiled in their origin, and the buyer would have to march / ship them home, but this had too many issues with intended functionality. For example: landlocked Brunswick would have trouble hiring Scottish Mercenaries to fight in their conflicts.


Field Marshal
112 Badges
Feb 4, 2011
  • Ship Simulator Extremes
  • Imperator: Rome Deluxe Edition
  • Imperator: Rome
  • Hearts of Iron IV: By Blood Alone
Hungary is emperor? HuH

Nice catch. I made this screenshot on a build that had a hilarious bug that was giving out Emperor Rank to any old nation.

Two more questions:

1) What will happen with company if their army was stackwiped but manpower of company is still there? And if it was drained completely, does that mean the end of such company?
2) Do generals of mercenary armies count in leader pool limit?

1. A stackwipe is a stackwipe, that mercenary company is gone, and will not be available for hire re-hire for another 10 years.
2. They do not. Since the generals of Mercenary Companies are explicitly tied to that army, they lose all flexibility afforded by your regular leaders, so it made no sense for them to eat into the leader pool limit.