cross the Rubicon

Cultural  

1. To make an irrevocable decision; it comes from the name of the river Julius Caesar crossed with his army, thereby starting a civil war in Rome. (See Rubicon.)

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cross the Rubicon Idioms  

1. Irrevocably commit to a course of action, make a fateful and final decision. For example, Once he submitted his resignation, he had crossed the Rubicon. This phrase alludes to Julius Caesar's crossing the Rubicon River (between Italy and Gaul) in 49 b.c., thereby starting a war against Pompey and the Roman Senate. Recounted in Plutarch's Lives: Julius Caesar (c. a.d. 110), the crossing gave rise to the figurative English usage by the early 1600s.

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Example Sentences

The Rev. Samuel Rodriguez, president of the National Hispanic Christian Leadership Conference, an association of 42,118 U.S. congregations, said Hispanic churches “are about to cross the Rubicon into thriving.”

From Washington Times • Jan. 24, 2023

In a way, they did cross the Rubicon, so to speak, and started describing him as a liar, and also tried to document what he was really up to.

From Salon • Dec. 30, 2020

Once you cross the Rubicon of the eighth decade, a year is a very long time.

From Slate • May 19, 2020

What finally made me cross the Rubicon of the show’s bluster was a video of some hummingbirds.

From The New Yorker • May 24, 2019

Mr. Botha had long talked about the need to cross the Rubicon, but he never did it himself until that morning at Tuynhuys.

From "Long Walk to Freedom" by Nelson Mandela