Many members of the French nobility had gone into exile and fought against the armies of the revolution, and the Duke of Enghien was one of them. In 1804 he was living across the Rhine river on German territory.
Napoleon heard an (untrue) report that Enghien was part of a conspiracy to assassinate him, and sent a hit team - sorry, a cavalry squadron - across the Rhine to kidnap him.
They brought him back to Paris, gave him a perfunctory military trial, and shot him. After that, things did not go well for Napoleon.
The idea that Napoleon would violate foreign territory in peacetime in order to murder an opponent was so horrifying, so repellent that opinion turned against peace with France everywhere.
As his own chief of police Joseph Fouché said: "It was worse than a crime. It was a blunder."
Since it seems almost certain that Khashoggi was murdered by the Saudi government - Turkish government officials have told journalists they have audio and partial video recordings of Khashoggi's interrogation, torture and killing - all of Saudi Arabia's "friends" and trading partners have some choices to make.
By the end of the year every major power in Europe was back at war with Napoleon. After a decade of war he was defeated at Waterloo and sent into exile on St Helena for the rest of his life.
So is something like that going to happen to MbS, too?
Nobody's going to invade Saudi Arabia but will they stop investing in the country, stop selling it weapons and buying its oil, maybe even slap trade embargoes on it? Since it seems almost certain that Khashoggi was murdered by the Saudi government - Turkish government officials have told journalists they have audio and partial video recordings of Khashoggi's interrogation, torture and killing - all of Saudi Arabia's "friends" and trading partners have some choices to make.
US President Donald Trump immediately rose to the occasion, declaring that he would be "very upset and angry" if Saudi Arabia was responsible for Khashoggi's murder, and that there would be "severe punishment" for the crime.
He even boasted that Saudi Arabia "would not last two weeks" without American military support.
The Saudis struck right back, saying: "The kingdom affirms its total rejection of any threats or attempts to undermine it whether through threats to impose economic sanctions or the use of political pressure.
"The kingdom also affirms that it will respond to any (punitive) action with a bigger one."
But Trump was only bluffing. He really had no intention of cancelling the US$110 billion of contracts that Saudi Arabia has signed to buy American-made weapons, because "we'd be punishing ourselves if we did that. If they don't buy it from us, they're going to buy it from Russia or ... China".
People have been turning a blind eye to the hundreds of civilian deaths caused by Saudi bombing in Yemen weekly for three years now. Why would they respond differently to the murder of one pesky Saudi journalist in Istanbul, even if he did write for the Washington Post?
The difference is that it's intensely personal - this is an absolute monarch ordering the killing of a critic who annoyed him but posed no threat to his power - and it's brazenly, breathtakingly arrogant.
MbS really thinks he can do something like this and make everybody shut up about it.
He is probably right so far as the craven, money-grubbing foreigners are concerned - like former British prime minister Tony Blair, who could barely even bring himself to say that Saudi Arabia should investigate and explain the issue, because "otherwise it runs completely contrary to the process of modernisation".
But if the foreigners will not, or cannot, bring Mohammed bin Salman down, his own family (all seven thousand princes, or however many there are now) probably will.
It is a family business, and his amateurish strategies, his impulsiveness and his regular resort to violence are ruining the firm's already not very good name.
He rose rapidly out of the multitudinous ranks of anonymous princes through the favour of his failing father, King Salman, but he could fall as fast as he rose. Killing Khashoggi was definitely a blunder.
