If we wanted to “go Medieval” on them, I’d suggest impalement. It’s cheap, and they just might fear it greatly.
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It worked pretty well for Vlad the Impaler:
The Turkish Army approached Targoviste four days after the Night Attack. The gates to the city were wide open, and they were greeted by an ominous silence. However, the sight before them was unimaginably grotesque. An endless field of decomposing corpses made up of thousands of Turks and Bulgarian Muslims impaled in every configuration possible.
It had the desired effect. According the 15th century historian Laonicus Chalcondyles:
The Turkish Army approached Targoviste four days after the Night Attack. The gates to the city were wide open, and they were greeted by an ominous silence. However, the sight before them was unimaginably grotesque. An endless field of decomposing corpses made up of thousands of Turks and Bulgarian Muslims impaled in every configuration possible.
Grrrr... One last try:
It had the desired effect. According the 15th century historian Laonicus Chalcondyles:
The Sultan’s army came across a field with stakes, about three kilometers long and one kilometer wide. And there were large stakes on which they could see the impaled bodies of men, women, and children, about twenty thousand of them, as they said; quite a spectacle for the Turks and the Sultan himself! The Sultan, in wonder, kept saying that he could not conquer the country of a man who could do such terrible and unnatural things.