The Reichstag Fire
Some have pointed, stupidly, to Kristallnacht, but the Reichstag Fire is much closer.
Crossing the Rubicon
This one is a little confusing because while it is often used to refer to an impossible restoration of some sort by the military, it could also refer to any irreversible choice, such as the one made in the early hours of November fourth.
Even the Guardian got in on it at one point: https://www.theguardian.com/commentisfree/2020/mar/06/biden-soviet-russia-status-quo-democratic-ussr
The Z Man on the Kremlinology: https://www.takimag.com/article/a-wilderness-of-lies/