Leonardo Da Vinci's Diege Engines

Leonardo da Vinci was an engineer who made siege engines that would kill people. He wrote a letter about how he could make flam, flaming goo that would land on top of soldiers coming into the castle and stick to them,. And he could make also little little bridges that would protect your guys from the same thing. But actually like most of the stuff in his letter was just bluster and he wasn't actually capable of a good portion of those things.