Supersessionist civil wars invite foreign intervention. It is typical of the phenomenon that today one side accuses the other of colluding with a foreign power, Russia. It is also typical that the president’s supporters treat the opposing force as secret regicides.

To look to the future, it is useful to look to the past.

The French Revolution was a supersessionist civil war. Calling it a “revolution” was politically expedient, a vanity of partisans. The French civil war pushed the state into a helter-skelter recklessness that may have lasted until the Prussian intervention of 1870. There is a case that French revenge for 1870 was a casus belli of the 1914 Great War, which itself can be thought of as a European civil war, 1914-1945.

The Russian Revolution was supersessionist civil war that not only wrecked Russia for a century, but also pulled all seven continents into a planetary Cold War.