"Sire, clear the square with gunfire or abdicate."
That was the message one of his generals gave the young czar Nicholas I in December of 1825, as thousands of civilians and soldiers massed in Senate Square to challenge his claim to the throne.
Nicholas gave the order, the cannons fired, and he and his heirs ruled Russia for another century, until Nicholas II was overthrown, and murdered by Bolsheviks.
Such was the moment Egypt's army faced on Wednesday, with thousands of backers of the Muslim Brotherhood encamped in Cairo, challenging its rule. The slaughter that ensued, 500 dead the first day and thousands wounded, means there is no going back.
The die is cast. The Egyptian army has crossed the Rubicon.
Egypt's generals cannot now hold elections that a coalition of the Brotherhood and Salafis might win. Were that to happen, many of them could wind up like the shah's generals, on trays in the morgue.
So where does Egypt, and where do we go from here?
While we Americans are babbling about a new politics of "inclusiveness," even some of the Twitter-Facebook liberals of Tahrir Square are coming to see Egypt as it is. Us or them.
And the one issue on which Egypt's Muslim militants and Egypt's militarists seem to agree is that the Americans cannot be trusted.
Two years ago, the United States celebrated an Arab Spring that began with the overthrow in Tunis and Cairo of dictators who had been our loyal allies. We then became the champions of free elections in Egypt, as we had been the champions of free elections in Palestine, until Hamas swept the board in Gaza.
When half of Egypt voted for the Brotherhood and a fourth for the more militant Salafis, we accepted the results and pledged to work with President Mohammed Morsi.
But Morsi failed as badly as Hosni Mubarak. So, when millions massed in Cairo's streets to demand Morsi's overthrow, we signaled our approval for a military coup.
Then, when Gen. Abdel Fattah el-Sisi seized power, imprisoned Morsi, jailed Brotherhood leaders and installed a puppet government, we refused to call it a coup.
Secretary of State John Kerry provided the comic relief by assuring us that the Egyptian army was "restoring democracy."
For two years, America has been loyal to no one, and consistent in nothing. Thus, Egypt's soldiers decided to do what they had to do to save their country. And if new elections are likely to produce a regime that threatens their Egypt, they will dump the democratic procedures rather than lose Egypt to the Brotherhood.