Vassal states are a feature introduced in the Warlords expansion of Civilization IV. A civilization can become a vassal to another civilization, either by choice or by force. The vassal contracts a series of obligation to its master, in exchange for military protection.

There are three types of vassals:

Peace vassals: one civilization chooses to become a vassal to another voluntarily, as part of a diplomatic exchange. Peace vassals may re-evaluate their decision to become vassals every 10 turns.

Colonies: a sub-type of peace vassals. The difference is how they are generated: the master chooses to “liberate” all their cities in a landmass different than their capital’s, ceding their control to a new leader that starts as a vassal.

Capitulated vassals: they become vassals as the consequence of a peace deal. AIs only capitulate when they are losing a war badly.

Vassals may also break free if they either lose too much territory, or if they grow strong enough to rival their master.

While having vassals is the default option, it is possible to choose to disable them in the Custom game setup. Here’s a list of pros and cons of vassals I have come up with:

Pros:

*Your vassals’ half population and territory partially count for the domination victory limits, making it easier and faster to achieve.

*Capitulated vassals make military games in huge maps a lot less tedious and reduce micromanagement.

*Vassals will always vote for you for a diplomatic victory (“diplomation”) and do not count towards the limit that blocks this victory if you can just elect you yourself, making it easier to achieve. (Note: it could be argued that this makes diplomatic victory less challenging and interesting).

*You can demand resources to your vassals (if they refuse, they auto declare war on you). This is good to get resources you don’t have access to in your territory or to gain extra resources for corporations. However, bleeding them dry will make them useless.

*You can order your vassals what technology to research. If they are not in a bad shape, they will actually finish the research before you do. You can direct them towards certain technologies and acquire them later in trade deals, while you focus on specific branches of the tech tree.

*You will always have full control over disputed tiles that fall under your city big fat cross (the first two rings), no matter what the culture percentages are. A city cannot revolt to join a vassal’s empire.

*Having vassals gives a small happiness bonus in all your cities (your citizens like to feel powerful).

Cons:

*Vassals screw up diplomacy. Despite what the diplomatic screen tells you, the real opinion of the AIs will be an average between their opinion of yours and their opinion of your vassals. It’s already bad that Civ4 has hidden diplomacy modifiers, but this is outright lying.

*It’s almost impossible to get rid of a peace vassal. In many years of playing I only remember one peace vassal becoming free, and it was a colony to another AI player. Some AIs (like Mansa Musa) will actively try to become peace vassals and then achieve peaceful victory conditions (culture or space), and there is very little you can do if you are their master.

*A human player cannot become a vassal. I’m not fond of different rules being applied to human and AI players.

*A vassal is supposed to adopt its master’s diplomatic stances (who they are at wat and at peace), but peace vassals do the exact opposite: if they are at war with another player, then their master also has to declare war upon accepting them as a vassal. There are few things worse in-game than being about to win a war only for your target to become a peace vassal, dragging you to another war with a bigger player with who you had had good a relationship until that point.

*Your vassals’ cities increase your own city maintenance costs.

*If vassals are enabled, cities in a landmass different than your capital get a big “colony maintenance” modifier to encourage eventually releasing them as a colony. This applies to any landmass and becomes ridiculous in archipelago maps.

*A colony is released with the same technology level than their master. The moment this happens you can say goodbye to any tech monopoly you had, as they will start trading techs with the other AIs.


Because of all these reasons, I usually play without vassals, unless it’s a very big map. I would be more inclined to play with vassals if it were possible to enable just capitulated vassals and leave peace vassals out, which in my opinion have the most problematic implementation. Perhaps there’s already a mod for that.

So, what about you? Can you come up with other points, for or against? Do you play with or without vassals?

I think the main problem here is with the Apostolic Palace. There are many game settings where getting at least one city in every empire with your religion is stupidly easy to do, which can give your voting block a majority for an early diplomatic win. I don't feel this is an issue at all with the United Nations; if you actually command a majority vote in the UN just by virtue of yourself and your vassals then you're probably on the verge of domination victory anyways.

As an aside I really wish there was the ability to turn off Diplomatic victory while keeping the AP and UN; I love all their other effects, but I find diplomatic victory to be too arbitrary for my tastes. Yeah, if you start taking vassals you better be ready to lone wolf it since the rest of the world is going to hate your guts. Honestly the way the AI does diplomacy in Civ 4 kinda pisses me off so I don't mind this ("Alexander: please join our war against the Mongols!"; 1 turn later: "Alexander makes peace with Genghis Khan") Definitely something to beware of. Never take a peace vassal if they look like they might be in a position to go for a peaceful victory type. While I agree, I understand why the developers did it. It would be way too easy to get culture victory if you could just find a powerful AI to be your master so you could stop producing military and focus on pure culture. This would probably be way too consistent and easy to pull off. It's not necessarily too bad on archipelago maps, since each land mass builds up its own "colony maintenance" separately. If there are only 2 or 3 cities on each landmass, that maintenance never gets too large. Since archipelago games tend to have higher commerce in general (since pretty much every city is coastal) it evens out in my experience. I generally keep them on, but I agree with your critiques; the feature is definitely rough around the edges.

A bit of a necro but you didn't get many answers so why not.

I strongly recommend playing without them. It's not as dumb as the AP, but it's close. In the AIs hands they just break map scripts that have multiple major landmasses at higher difficulties because an AI always ends up snowballing the entire continent by astronomy becoming a runaway that's nearly impossible to defeat. It's also annoying on Pangaea and related scripts because the AI has a tendency to beg for protection from the biggest AI a little bit before you kill them which is a giant pain. Not unbeatable like the continents snowballs, but still annoying. The fact that certain AIs are totally capable of winning a cultural victory while vassalized with no recourse is also pretty annoying albeit something you can play around.

In human hands, it's even worse. Once you know how the mechanic works, it is hilariously exploitable. Get some military tech lead (important because you need a clean victory against the stack to get enough war success to vassalize). Declare war on some average strength or weak AI you share borders with. Wait for their stack to attack you. Kill the stack. You can probably vassalize, but if you can't, get their landmass lower than yours by taking a few cities and vassalize as soon as you can. Repeat with your vassal's borders counting as your borders for the "shared borders" thing. From here on just killing the stack should be enough to get the vassal. Repeat until domination while avoiding civs with above average power ratings because it's impossible to vassalize them. They make things a bit quicker if you don't exploit it, but it's not game changing and there's a good chance you'll unintentionally exploit it anyway because killing their stack and then mopping up is the best way to war against a remotely even AI anyway.