Conquering Disease: Tips to Combat Plagues in CK3

During the medieval era in Crusader Kings 3, there are countless concerns to juggle. You have succession issues, troublesome neighbors, and significant holy wars to manage. However, one of the most unpredictable and dangerous threats you face is plagues. No amount of planning can shield you from a sudden outbreak of typhus that could wipe out you and your entire court.

Plagues represent an unseen menace—something that can’t be completely prevented and is often erratic in nature. They have the potential to undermine the stability of your realm, leading to a loss of tax revenue and disrupting the networks of support you’ve carefully cultivated with your vassals. Here’s an overview of how plagues function and some strategies to lessen their impact.

Understanding Plagues

The first critical point is that plagues largely emerge randomly. There isn’t a way to eradicate them entirely, nor can you predict their duration. The severity of a plague is set at its inception; an apocalyptic plague will always remain so, just as a minor plague will maintain its lesser status.

What you can influence is how widely a plague spreads, which is your best strategy for survival. Each plague is tied to a specific disease, and contracting it can be catastrophic for any character. Fortunately, plagues are not transmitted by individuals but by locations. Thus, unless your character travels to an infected area, they won’t catch the disease from anyone in their own court.

Plagues spread from one barony to another, beginning from a random initiation point. However, a higher Development level increases the likelihood of plague outbreaks and the chances of becoming infected by default.

What Influences Plague Spread?

As with real-world diseases, once a plague emerges, your priority should be to contain it and prevent its spread throughout your realm. There are several strategies you can adopt, but let’s first explore how plagues propagate naturally.

Once a plague establishes itself in a barony, it can infect individuals and expand beyond its initial area. This spread is partially influenced by your Disease Resistance. The actions of infected individuals do not dictate the spread—it’s determined by the plague itself.

Boasting a high Disease Resistance provides two main advantages: fewer infections in the affected barony and a lower likelihood of that area becoming infected initially. Plagues typically spread to neighboring baronies and do not jump across multiple regions. Therefore, if a plague starts far from your capital, it’s less likely to reach you if your intermediate baronies have high Disease Resistance.

Proximity to water also plays a significant role in plague spread. Baronies near bodies of water, especially rivers, face an increased risk of infection in adjacent regions. The best countermeasure is to develop structures like Hospices within those baronies.

Even after a barony becomes infected, maintaining a high Disease Resistance can minimize the total number of infections there. While it’s impossible to wholly prevent plagues, especially as your Development increases, you can still make efforts to limit their effects.

Dealing with Plagues

Now that you understand how plagues function, it’s time to consider what actions you can take as the player and ruler to control their spread. You can focus on two primary strategies:

Building facilities that improve Disease Resistance is a long-term goal, and it’s beneficial to have them in most baronies to mitigate infection rates. While it is the safest approach, it can also be costly. Since construction takes time, you can’t simply erect these buildings when a plague approaches.

This makes it valuable to have your Personal Physician actively managing Plague Control. For an additional 0.30 Gold each month, you gain a substantial boost to your entire realm’s Disease Resistance.

Recovering After a Plague

After a plague has affected your territory, it’s crucial to track where the outbreak occurred. Any region hit by a plague will have experienced a decrease in Development, often significantly. A debuff typically lingers for a couple of years, although an astute Personal Physician may mitigate some of the damage.

It’s advisable to send your Marshal to the affected areas to increase control, helping recover lost tax revenue faster. Additionally, allowing your Steward to enhance the Development in those areas can help with recovery, even if the improvements are not direct.

While plagues are a frequent and devastating issue, effective preparation is your best defense. Ensure that you do not neglect the construction of Hospices, as these can save numerous lives. If a plague reaches your capital, consider the option to Isolate the Capital. While this decision might upset your subjects in the short run, it’s a far better alternative than risking the lives of your entire court.