Worlds of Design: Pestilence & Plague

Plagues have made a big difference in world history, and may in your fantasy world. In the course of studying military and diplomatic history over most eras I’ve encountered a lot about this frighteningly frequent occurrence.


Picture courtesy of Pixabay.

The condition of the people was pitiable to behold. They sickened by the thousands daily, and died unattended and without help. Many died in the open street, others dying in their houses, made it known by the stench of their rotting bodies. - Giovanni Boccaccio (1313-1375)

Absent widespread healing or vaccines, plagues have historically been a fact of life, one of those things you hoped to avoid but sometimes could not. The effects were far-reaching. In building a world, you can ignore plagues, just as you can ignore famines and extended droughts that can bring down empires and even civilizations, or you can incorporate them into the history of your world. Whether that will increase the immersion of your game depends on your players. I’m going to talk about some characteristics of plagues and how you can incorporate them into your world building.

Lethality and Randomness​

The Black Death of the 14th century (also known as the Pestilence or the Great Mortality, peaking in Europe1347-1351) helps provide a guide to the lethality of historical plagues. Depending on the affected location, between a quarter and a half of the population died. Plagues in general are random, so that there were locations such as Milan, Italy that were essentially free of the Black Death. If you look at a map of the effects of the Black Death, you can see this variability for yourself. Some plagues almost always killed anyone who was infected, while others saw many recover and possibly gain immunity. Plague usually affected everyone, young and old.

It Kept Coming Back​

Historical plagues didn’t just peter out or disappear never to be seen again. They kept coming back in waves, with periods (often many years) in between that were relatively plague free. Obviously, there were no vaccines, and even if the plague were one that you became immune to after contracting it, there were people who had not yet contracted it, plus younger people born since the last outbreak. In some areas forms of plague continued to occur periodically into the 17th (and rarely 19th) century!

After the fact, a plague could radically change the nature of society. After the Black Death, the standard of living rose significantly. Ordinary people ate better because there was a lot more food (especially meat and fish) in relation to the population. The poorer land went out of cultivation and reverted to nature, for lack of farmers - but that meant on average people farmed more productive land. Laborers were paid more because there was a shortage of labor. Plagues had far-reaching social effects, e.g. widespread persecution of minorities and lawlessness. Effects were so pronounced that the time of the Black Death is sometimes regarded as the end of the Middle Ages.

The Fall of the Western Roman Empire​

A fairly recent explanation of the weakness and fall of the Western Roman Empire is that it was depopulated by plagues 180-250 CE. This is rarely touched on in the literature of the time (perhaps because it was so common), but archaeological investigation of Roman cities shows a great contraction of the lived-in area, indicating a much lower population long before the actual failure of the Empire. This is not the only reason of course. When you talk about the fall of Western Rome, the question is always why didn’t Eastern Rome (what we now call the Byzantine Empire) fail? Eastern Rome had a much higher population, far more cities, and could suffer a series of plagues more readily than the West.

Yet the Byzantine Empire suffered a great plague, possibly as bad as the later Black Death, in 541-549 (not disappearing entirely until the 700s). This doomed Emperor Justinian’s efforts to reunite the full Empire, for lack of manpower, though he did recapture much of Italy, North Africa, and even southern Spain before the plague.

In pre-Roman-domination times, a plague killed many Athenians including their leader Pericles (d. 429 BCE); some historians believe his death doomed the Athenians in the Peloponnesian War with Sparta.

What This Means for Your World​

Fantasy worlds are different from the real world in the availability of magic that can cure diseases. The question is always how much healing is available in comparison to the size of the population? We could say that the elites (such as Pericles) are much more likely to survive a plague thanks to magic, as opposed to historical plagues where anyone from an Emperor on down (including several Roman emperors who died from pandemics) was just as susceptible as anyone else.

As you build the history of your world a plague can make a huge difference, especially a plague as bad as the Black Death or the Justinianic Plague. In a fantasy world with many intelligent species, a plague might affect only one species to its detriment. When someone asks why there are so few of a particular species, an answer might be disease. Even today birdwatchers observe that house sparrows rapidly disappeared from much of the countryside, possibly because of disease.

Your Turn: How have you implemented plagues in your campaign?
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Lewis Pulsipher

Lewis Pulsipher

Dragon, White Dwarf, Fiend Folio
you can generally expect significant plagues like the Black Death to outstrip the ability of spellcasters to cure it.
I can remember some discussion on this subject way back in 1E days, and my general thought was 'plagues can naturally spread faster than the limited number of clerics around who can cast 'cure disease' can stop it.' Plus, there's the 'the PCs won't know it, but anyway...." idea that maybe magical curing won't give any kind of immunity to a disease that recovering naturally would....

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fun fact, about that eye burning nose overloading patchouli incense. It was used to cover the smell of decaying bodies. The magical version must be capable of scraping away the uter layer of skin for sanitization :p


Solitary Role Playing
I eliminated real world science in my game :) No gunpowder, gasoline / internal combustion engines, miracle medical drugs, etc. In 1974 my original players were board / miniature wargamer history nerds :D They would have been blowing up dragons and building machine guns and tanks in no time... so bye bye science, hello the elements air, earth, fire, water, and my number five - spirit. Saved me from explaining just how difficult all those "simple" ideas would be to develop too. Changing how the world works can account for the rather wonky game physics as well.
Interesting. I had a player who wanted to build a flame thrower. He had a lot of difficulty separating his knowledge from his character's knowledge.

You might like Dies the Fire by Stirling:


When players want to use modern knowledge in the game always remember that you need far more than just the theoretical knowledge to build something.
Milling gunpowder is dangerous, especially when you have no training in it and you will usually end up with something that produces more smoke than explosions at first. And even when you have that, to make guns you need better metallurgic knowledge than what might be available, meaning the best you can come up with are for example handgonnes or cannons so large and heavy to be unusable in field battles.

Also in the time where plate mail was common firearms and flamethrowers existed. They were not superweapons which defeated everything.
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Dragon guano as a source of ignition / combustion just makes sense :D Do you have different effects for different dragon's guano?
Haven't really gotten that far. And, well, haven't really needed to. Simply making dragon guano the main ingredient in gun/smoke powder means that I don't have to worry about it becoming too popular or anyone being able to mass produce it.

And, it gives kobolds some REALLY fun stuff to play with. :D

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