How did a besieged city/castle defend itself vs. catapulting diseased dead bodies into it?

Question

I was a bit shocked to read that diseased dead bodies/animals where catapulted into besieged castles/towns. Biological warfare in the middle ages. But this "method" of warfare had probably a lot of advantages and disadvantages (no own losses, but patience needed and no chance to plunder).

Was this a common method in the middle ages, or was it only used in extreme situations, when military options didn't work/succeed? Had a besieged town any chance/method to defend itself vs. either such attacks or its consequences. Were there any remedies vs. plague/infection diseases? I didn't read anywhere about capitulation in such situations, when threatened by this "catapulting".

Answer 1

The first example of catapulting plague victims into a besieged city was that of Caffa (Modern day Feodosia) in the Crimea. This was in fact the first account of plague in European history.

Caffa had been under siege by the Mongol (aka. Tartar or Golden Horde) army. The siege had been protracted. First starting in 1343, it was lifted by the arrival of Italian reinforcements in January 1344. The city was again under siege in 1345 however, a year later the Mongols started to die from a new disease - plague.

The Mongols tried to force the siege by catapulting victims corpses into the city and they were successful in spreading the disease to Caffa. Even during the siege, Caffa's sea ports remained open and trade was conducted by Italian merchants with other nearby cities under Mongol control. Thus from here the plague was spread out to the rest of Europe.

Despite the use of plague as a weapon, it was the Mongols who capitulated to Italian demands and opened up to more trade. I think it likely that the Mongol besiegers were more badly affected by the plague than the Caffa inhabitants within.

Gabriele De' Mussi was a witness to these events. He wrote:

Among those who escaped from Caffa by boat were a few sailors who had been infected with the poisonous disease. Some boats were bound for Genoa, others went to Venice and to other Christian areas. When the sailors reached these places and mixed with the people there, it was as if they had brought evil spirits with them: every city, every settlement, every place was poisoned by the contagious pestilence, and their inhabitants, both men and women, died suddenly. And when one person had contracted the illness, he poisoned his whole family even as he fell and died, so that those preparing to bury his body were seized by death in the same way.

There are only a few other examples of this. During the siege of Thun-l'Évêque in the Hundred Years' War, dead animals were thrown over the walls. However, there was no plague in the animals.

The siege of Karlstein Castle in Bohemia in 1422 saw the attackers throw dead human bodies over the wall, though again without plague infection.

It would seam that this form of attack is not as popular as some sensationalist historians make it out to be. Also the effects seem to be unpredictable. In order to have plague victims to throw over the wall, plague must be present in the besieging army. Not something you would want. Indeed disease is as much a problem for the besiegers as it is for the besieged. Sometimes a siege has been broken because the attacking army came down with cholera, dysentery or other.

Answer 2

Your main question has been pretty well answered, but I'd like to clarify a few points:

• If the attackers had plague victims to toss over the wall, it means they were also exposed to the plague. Which might adversely affect their ability to maintain the siege.

• Even an extremely virulent plague like the Black Death only killed something like a third to half of the population on average (it varied a lot - some towns were completely wiped out, but that wasn't the norm). Horrifying as that is, it wouldn't necessarily be enough to force a surrender. And most diseases were significantly less fatal than that.

• Most contagious diseases disproportionately kill the very old, very young, or otherwise ill - in other words, the portion of the population that was least likely to be helping with the defence anyway. Depending on how callous they were, the defenders might even be happy to see their food supply stretch that much longer.

• Generally the idea of a siege is to make conditions so miserable that the defenders decide to surrender (or that a mob of the people being 'protected' oust the defenders and surrender). Disease could certainly speed that process up, but it didn't fundamentally change the dynamics of the fight. If the threat of starvation didn't break the defenders' morale, the threat of disease probably wouldn't do it either.

I'm not trying to knock the effectiveness of spreading diseases, just to point out that it wasn't a magic bullet.

Answer 3

The other issue is that because disease was not fully understood, the efficacy of this maneuver would be mixed at best. Sure, if you send plague victims over the wall, that could give the people inside of the city the plague. However, the belief at the time was that disease was caused by bad smells, and so a dead, decaying horse would have been believed to have just as large of an effect. Of course, it might not have any effect at all except to make the city slightly stinkier.

Also, as I think has been implied, this was something of a nuclear option for invading armies to use. By and large, the whole point of attacking a city was that you wanted to take the city for yourself, or at the very least you wanted to sack it and take all of its gold/women/etc. You infect the city with the plague, there's really no going in there. The Mongol example that Anixx provided is a great one, actually, in that I believe that the city of Kaffa was one that the Mongols had decided they were going to just destroy (the Mongols had a general belief that if you as a city surrendered to them and then rebelled, you were to be wiped out this time around).

Answer 4

How do you defend against the plague? You seal up any house that gets hit. This was how they controlled the plague in Milan so I'd expect other cities and fortresses took similar measures at various times. Biological Warfare was quite common in the ancient and medieval world.

Answer 5

I'm not sure that this was all that common as a means of overtaking a besieged castle. Perhaps more than anything else, it was intended to have a psychological effect on the occupants. As for how they defended themselves, quite honestly they couldn't. The most common means of handling this was to designate individuals who were responsible for gathering the carcasses as soon as possible and burning them to try to prevent the spread of any disease. I don't recall reading anywhere about a siege breaking because of the plague or any other disease. More often than not it was due to lack of food or water. I believe there may have been some hope by the attackers that the diseased or rotted bodies would hit the town's wells and spoil any internal supply of water that the town may have.