7 Devious Ways to Defeat a Medieval Army

Could you defeat a medieval army without resorting to a clash of arms? A 10th century Byzantine military manual offers several tricks that could be used to devastate your enemy.

The Sylloge Tacticorum is one of several Byzantine handbooks on military tactics that has survived to the present-day. Its purpose was to guide a commander during a campaign, offering advice on a wide range of scenarios and plans.


Besides noting the standard ways of attacking and defending, the author of this manual also includes several methods to cunningly strike at an enemy, although he does not personally approve of them. He writes:

We compiled this book judging that these stratagems and others of the kind should be recorded not in order to be used by us against the enemy (for I believe that they are unworthy even to be mentioned in a Christian context), but so that our generals may be able to guard against them by knowing exactly the cunning plans of the enemy concerning food and drink, especially when they encamp in enemy territory.


However, it should also be noted that the author usually does not give any defence against these schemes, which might indicate that he added them in so they could be used by the Byzantine generals – and that his moral concerns might have been exaggerated. Readers will note that these methods can be considered a form of chemical warfare, which would be targeted at the enemy when they were not expecting it.

1) Putting the plague into bread loaves

The first scheme mentioned by the Sylloge Tacticorum involves a somewhat complex way of infecting the enemy with plague. The first step is place a tree-frog or a toad into a vessel with a viper. The vessel is sealed up airtight until both animals are dead. Their bodies are then ground up and boiled in water. This water is then used for making loaves of bread.

The commander now has to make the enemy soldiers eat this bread. One way is to feed it to prisoners, then allow them to escape. Those soldiers will likely return to the enemy camp, and soon enough they will not only become ill with the plague but will also spread it to their comrades “just by living alongside them.” The one drawback to this plan, according to this manual, is that those who prepare the loaves of bread will also fall victim to the plague.

2) Poisoning the wine

The Sylloge Tacticorum offers two methods for poisoning wine. The first technique involves adding monkshood, boxwood or hemlock to your own supplies of wine, and then have your troops take flight and abandon them. The enemy then comes up, finds the wine “and drink their fill and thereby endanger themselves.”


The author then gives this recipe that will cause the enemy soldiers to sleep for days:

When somebody thoroughly grinds and smooths two litra of Theban poppy juice, myrrh, one part of lettuce seed, one part of henbane juice and two parts of mandrake juice, then pours them into wine, he will make those who drink it sleepy for two or three days. On the other hand, when somebody puts vinegar in their noses, he will cause them to recover.

3) Sabotaging the water supply

Attacking the water supply of an enemy army seems to be a useful technique, and this military manual notes a few powerful poisons that could be added to water, including ground-up pufferfishes, myrtle spurge, fish lard or manure.


4) Destroying the land

The Sylloge Tacticorum notes that one tactic that could be used is to make land unusable for agriculture, for at least the length of a season, which would prevent an enemy army from harvesting its crops. This can be done by ploughing into the soil hellebore or salt.

5) Withering the trees

Similarly, the text notes a way to kill off trees:

Every kind of tree, apart from the apple-tree, becomes desiccated if somebody inserts the sting of a stingray into its roots. Some say that the rind of beans placed into the tree roots also dries them up.

6) Attacking the horses with chemicals

Various chemical weapons can also be used against the enemy’s horses according to the Sylloge Tacticorum. It advises that your infantry carry with them hand-pipes holding spurge juice, which can then be sprayed into the horses nostrils as they charge against you. The animals when then turn to flight. Other potions are apparently powerful enough to kill horses, such as the bile of a sea-turtle. The effects of this poison can be counteracted by adding saffron and wine to the horse’s nostrils and mouth. The text even offers this strange method:

When the ankle of the right forefoot of a wolf is cast in front of a four-horse chariot, it stops the horses. Well, if it stops four horses, it would work much better on those that are in formation. We will give these ankles then to a few slingers, in order to shoot them into the enemy formation. Each ankle will not harm only one horse, but all those which happen to run over it.


7) Burning weapons without fire

Finally, the Sylloge Tacticorum offers this interesting set of instructions on how to burn the enemy’s weapons without fire:

Put equal portions of of native sulphur, rock salt, ashes, cedar-tree, and pyrite stone in a black mortar, when the sun is at its peak. Mix together with black mulberry sap and free-flowing Zakynthian liquid asphalt, each in equal portions. You should grind it until it becomes sooty coloured. Then you should add the smallest amount of quicklime to the asphalt. However, as the sun is at its peak, you ought to pound it with diligence and to protect your face entirely. Then, it should be sealed in a copper vessel, so as for it never to see the rays of the sun. The wagons of the enemy should coated while it is still night. All will be suddenly burned, when the sun shines on the moderately.

This text has recently been translated by Georgios Chatzelis and Jonathan Harris in A Tenth-Century Byzantine Military Manual: The Sylloge Tacticorum, published by Routledge. Click here to buy it on

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Top Image: A scene of Byzantine warfare from the Madrid Skylitzes