Educate me on the most horrific atrocities in history. Nothing

Scaphism. Persian torture-execution.

"[The king] decreed that Mithridates should be put to death in boats; which execution is after the following manner: Taking two boats framed exactly to fit and answer each other, they lay down in one of them the malefactor that suffers, upon his back; then, covering it with the other, and so setting them together that the head, hands, and feet of him are left outside, and the rest of his body lies shut up within, they offer him food, and if he refuse to eat it, they force him to do it by pricking his eyes; then, after he has eaten, they drench him with a mixture of milk and honey, pouring it not only into his mouth, but all over his face. They then keep his face continually turned towards the sun; and it becomes completely covered up and hidden by the multitude of flies that settle on it. And as within the boats he does what those that eat and drink must needs do, creeping things and vermin spring out of the corruption and rottenness of the excrement, and these entering into the bowels of him, his body is consumed. When the man is manifestly dead, the uppermost boat being taken off, they find his flesh devoured, and swarms of such noisome creatures preying upon and, as it were, growing to his inwards. In this way Mithridates, after suffering for seventeen days, at last expired."

—Plutarch, Life of Artaxerxes

Nanking.