Eli5: Why was it world-changing that Caesar crossed the Rubicon?

Question

Eli5: Why was it world-changing that Caesar crossed the Rubicon?

In: 1397

Answer 1

There are loads of great answers already detailing the pop culture understanding of the term (ie julius Caesar crossing the river with his army amounted to a declaration of war, a step beyond which it was impossible to turn back).

However! TIL that this isn’t actually true.

Comment
byu/RusticBohemian from discussion
inAskHistorians

tl;dr – The Senate was the aggressor, not Julius. They forced his hand by repeatedly attempting to strip him of his power, illegally removed his allies from the senate, etc.
The “crossing the Rubicon” idea came from a poem written 100 years after the event, and probably had no particular significance to the people of Julius’ time.

(So… it’s essentially a pop culture meme of its day, rather than “real history”?)