As far as I can tell,
"Crossing the Rubicon" means passing a point of no return.
It's not necessarily bad, or a sign of impending doom. Just that there's no going back.
The Rubicon being in the general area of Rome, in the time of Rome.
The Maginot Line - that is a French thing.
I have the impression that the French realized that they were probably going to have to fight Germany, and they needed a CLEAR way to measure Germany's hostile intent.
They created a line of reinforced forts, bridges, roads etc. and named after some French dude.
When Germany crossed that, that was an obvious sign of hostile intent, and the signal for France to fight back.
So it was like a Rubicon, with a condition attached, such as "OK this is the part
(https://en.wikipedia.org/wiki/Maginot_Line#/media/File:CarteLigneMaginot.png)
https://en.wikipedia.org/wiki/Andr%C3%A9_Maginot
Of course, Wall Street was also financing WW2 Germany.
http://tarpley.net/online-books/george-bush-the-unauthorized-biography/chapter-2-the-hitler-project/
Separate Note:
Trebitsch Lincoln - the name of the AIPAC 1920's, Hitler's first big political backer.
Who really was Trebitsch Lincoln ?