This is the sixth in a series of reviews looking at the evolution of Europa Universalis IV. See the previous reviews here:
Europa Universalis IV: A Fantastic Point of View
Wealth of Nations: National Trade
Res Publica: A Tradition of the People
Art of War: Reform-Minded Patch
El Dorado: Expansion of Gold

The sixth expansion for EU IV concentrated on government forms, and administering a country, while the patch introduced major changes to the basic stats of provinces, buildings, and sieges. Common Sense was released on June 9th 2015 alongside patch 1.12. Some general tweaks to the new systems came in patch 1.13 (which is the version I’m reviewing) in late August.

New Developments

In the original two games, each province tracked population, which fed into tax and manpower numbers. By EU IV, this had been abstracted into each province having a base tax, a production amount (which generated money, and value for the trade system), and an amount of manpower. Now all three of these were unified into one system where the total of everything added up to its development.

With the new system, each base tax generates one ducat (yearly) and 1% local spy defense (this was changed to taking over the recruitment bonus of manpower later). Each point of production generates 0.2 trade goods per month, and reduces shipbuilding time. And each point of manpower adds 250 to the nation’s manpower pool, reduces recruitment time, and promotes the growth of fortification garrisons.

The total development in a province has a number of effects: Each point generates provincial trade power, raises the supply limit, adds to the national land and naval force limits, and reduces missionary strength (making prosperous provinces harder to convert). Also, development determines a province’s cost in a peace, the amount of overextension it generates, and other similar things.

As with the old system, you can get events that will add to, or otherwise change around development points, with the expansion, you can also buy development with the appropriate monarch points. The base cost is 50/development, but that is increased by some terrain types, and it gets more expensive as development goes over 10. However, a major part of the idea is for small countries to be able to ‘grow tall’, pumping spare monarch power into the provinces they do have, and making them rich.

Building Forts

With development as a new thing to manage, the building system that had carried over from Divine Wind was done away with for one with fewer buildings, and more choices to be made. Instead of the six categories with six levels each, plus manufactories, plus various unique buildings, there are now 10 separate buildings, most of which have two levels (forts have four levels, trade buildings have three, and universities have a single level), plus five types of manufactory.

More importantly, each province can now have a limited number of buildings at all, and forts count against this. The base is one slot (for having a city; i.e., not being a colony), with bonuses for good terrain (farmlands add two slots), and an extra slot for every 10 development in the province, so only the very richest provinces can even have all the possible buildings.

Forts got a very important change, that reworks how wars work overall. It had always been the case that each province would have a fort, with the level going up as technology unlocked more types, and money was available to upgrade them. Now, the limited building slots mean there just isn’t room, and forts are now expensive.

Maintaining a fort now costs 1 ducat per month per level. Putting a basic fort in every province would wreck the economy of the wealthiest nations. However, forts now protect all friendly provinces adjacent to them, as well as their own province. Moreover, they have a zone of control, which keeps enemy troops from marching through any province adjacent to it.

So instead of wandering around the countryside, seeking out an enemy army to defeat, and sending out lots of small detachments to individually siege every province, movement is constrained by uncaptured forts. Once adjacent to an enemy fort, your only movement choices are to move out of range (or the country as a whole), or to the fortress province itself. Once in a province with an enemy fort, you can only exit out of the country (if it’s on a border), or back to where the army entered the province from.

You still besiege non-fort provinces, and they will fall to you after one month (/siege cycle), but if you have not taken or besieged any adjacent enemy fortresses, it will revert back to the enemy one month after you leave.

Since there’s fewer of them, sieges are now much bigger operations, needing three times as many troops as before. Also, each ‘building level’ generates two ‘fort levels’ in terms of the bonuses against siege rolls. Every capital gets one free fort level, even if there’s no building there (so even the tiniest, poorest, country has a +1 fort in its capital), which gives capitals all the in-between ‘odd’ levels.

The siege rolls changed slightly in that rolling a ‘1’ never generates progress, and instead kills 5% of the besieging army from disease. Also, ‘obsolete’ fortresses have a penalty, making them quicker to siege, as do fortresses that have less than half of their garrison. Overall, sieges tend to take a bit less time than they used to when a military is well-equipped for them; but the higher fort levels (especially in a capital) also lead to some very long and expensive campaigns.

An existing fort can also be mothballed, giving it half maintenance cost and no garrison. This is a great way to have defenses, and a good peacetime budget. However, if war breaks out the fort may need to be reactivated, and it will take time for the garrison to grow back to full, allowing a swift-moving enemy to get the bonus for it being under half strength.

A smaller change also had a big effect on wars: Armies and navies are now locked into going to a province once they are halfway there. That prevents a lot of fiddling around, and ‘faking’ going to a province, and makes actual interception of forces possible, as you might not get there ahead of an army, but you can get there before he can leave again.

Rate My Government

A smaller change to the overall game was that all nations now have a rank, as a duchy, kingdom, or empire. This has nothing to do with governmental forms, but purely with how large and powerful it is. This system exists without the expansion, but is seriously downplayed as changing ranks is generally disabled.

Generally, being a higher rank makes it less likely to be made a vassal (for the AI), and adds to the number of diplomats and military leaders available. Some forms of governments also get scaling bonuses, where it gets better with a higher rank, and the tribal governments generally ease their penalties at higher rank.

Only a handful of countries start as empires (including Byzantium, which is appropriate, as you generally don’t go down in rank). Small duchies can become kingdoms once they have 300 total development, and kingdoms can become empires at 1000 development. There’s a few extra wrinkles thrown in, such as member states of the HRE are always duchies, with electors capable of becoming kingdoms.

It’s a fairly small change to things, but there’s enough wrinkles to it all to make it a fairly neat passive subsystem. Large countries get a little more diplomatic weight, an extra leader to go with all those armies (and fronts), and the AI is protected from predatory vassaling players.

Free Cities

The patch introduced a new unique government type for the HRE, the free city. They get bonuses to trade and development, and in return increase imperial authority and revenue. The city also gets extra protection from the Emperor (attacking one isn’t advised). And, being a free city, once one gets a second province, it stops being a free city, and reverts to an oligarchic republic.

Mostly, this is an attempt to re-work the internal forces of the HRE. Since they get extra protection from the emperor, and they provide money and authority to him, there’s a lot more motivation to keep the member states small, instead of slowly growing to a small number of larger states.

Along with this, the main workings of imperial authority was also redone, to have more monthly changes instead of big events. Having more member states in the HRE, and having more free cities and electors was rewarded. However, as having ‘heretic’ princes lowers authority, it means that reform of the empire is much harder once the Reformation gets going (…which seems like a good side effect).

So You Say You Want a Constitution

The expansion included a new feature for some government types. The late game Constitutional Republic and Constitutional Monarchy, now have parliaments, along with the unique English Monarchy government (only available with the expansion).

Any government with a parliament will regularly have debates (well, you don’t have to, but it costs legitimacy to ignore it). There’s a large number of different possible subjects for debate, most of which will generate a bonus for the next decade, and a few can generate stability, or extra base tax.

When one is proposed, it is debated with a 0% chance of passing. To get it to pass, one must bribe a number of seats in the parliament, which are each attached to a particular province. Each seat gets a bonus to taxes, production, and manpower, but the more seats there are, the more of them need to be bribed for a decent chance of winning a debate. The bribes are varied, and what each seat asks for will depend on the province, but it can run from gold, monarch power, army tradition, to more specialized things like fervor (the Reformed religion special mechanic), to imperial authority (for the Emperor of the HRE).

Since it grants extra bonuses, it is rather like the ‘extra powers’ that some religions get through various expansions. At the same time, its a nice touch for England, as it does give it an extra dose of early flavor, like the other unique governments earlier expansions had added. And it does come with a cost, as a failed debate costs prestige, and winning a debate not only costs the bribes mentioned above, but as the debate goes on, there will be a number of events popping up for further bribes to the seat (almost always money), or lose support.

In the Name of God

When EU III came up with the governmental type system, theocracies were an off-branch for a few governments, with the papacy being a special form. Now that monarchies and republics each had their own mechanic (legitimacy and tradition), theocracies got devotion as an equivalent in the expansion.

This doesn’t generally slowly move up and down a little every month as with other two (it will with positive or negative stability, but other effects are more rare), but there are events that will shift things. Unlike the others, devotion has no effect on unrest or stability, but it does affect taxes and prestige, as well as papal influence (if Catholic) or church power (if Protestant).

Also with the expansion, most theocracies get an event to choose an heir (it’s normally just a random new ruler at the former’s death without it). This can be a fairly long list, and it’s really just a choice between different immediate bonus and penalties (money, prestige, devotion, ect), with the heir’s abilities being decided after the decision.

More Religion

Paradox continued to add nuance to religions, adding Tengri to central Asia (replacing some of the shamanist area), and adding Zoroastrian for one province (and possible CK II conversions). Buddhism was split up into Vajrayana, Mahayana and Theravada branches. All three versions get increased tolerance of heretics, but differ on giving bonuses to morale, advisors, or ideas.

The expansion also gives all three versions of Buddhism a new mechanic, karma. This is a 0 to 100 slider, like several other scales in the game, but the general goal is to balance it in the middle instead of just running it up to max. At low karma, you gain discipline and lose diplomatic reputation, while high karma is the opposite, and balanced karma gives a stronger bonus to both. The reason for splitting Buddhism up was that each version gets its own events, or its own choices for the same event, so that each one interacts with karma and the world differently.

At the same time, the Protestant religion got a new mechanic with the expansion. Church power accumulates, a bit like fervor does for Reformed, and allows purchase of church aspects. Power grows at rate equal to one tenth the total monarch power generation of the country, multiplied by the nation’s religious unity percentage, so a large country split between competing religions will have a hard time getting anywhere until things get under better control, while a one- or two-province minor can generate power quite fast.

Instead of the Reformed mechanic of using power to keep a bonus active, it’s technically a one-time purchase. But there are twelve possible aspects, each with its own bonus, and only three can be active at a time, so once there are three, they can be slowly changed out for other bonuses as more church power accumulates.


Originally, you needed this expansion to be able to manually increase development in a province, which made this very much a ‘must get’ for anyone. The game was just as playable as before, but there were too many references to increasing development to not feel some aggravation over not being able to do it. However, patch 1.28 moved this ability to the main game, so this expansion is no longer needed for that.

That leaves the major reasons for purchase as the new government and religion mechanics. As such, it makes a great companion expansion to Wealth of Nations, as they both enhance India and surrounds and the Reformation religions. Parliaments are a little limited in scope as they belong to later mid-game governments, though they’re a great addition if you wish to play England (which is a good country to play as).

Government ranks (and changing them) are a tiny feature, but if you’re playing to expand from a small start, being told you’ve ‘ranked up’ is at least as good as the actual reward. And finally, there’s the theocracy mechanic, which I feel should be in the main game (though it comes up rarely enough), alongside legitimacy and tradition. Overall, there’s a bunch of smaller things here, and I don’t see this as a meaningful expansion for a new or occasional player. But if a couple of the features strike your fancy, there are some good ones here still (and keep in mind that the ‘national focus’ feature from Res Publica comes with this expansion as well, if you don’t have that).

On the patch side of things, this was another major shakeup of how the game is played. The new siege and committed movement systems make a big difference in war. In some ways, it’s quite easy to miss the more free-wheeling movement and countermarches of any of Paradox’s games until this point, but there are compensations. You really need to think about how your forts ensure the protection of your realm, and how to take apart an enemy’s defense line.

Wars on land are a little more sedate now, though there’s still scope for more mobile warfare away from congested Europe. Coupled with some minor interface changes that made a lot of on-map things more visible, it was a great update to the game.