When Julius Caesar crossed the Rubicon in 49 BC, he said, "Alea iacta est". In English, it means, "the die has been cast". Now we associate the phrase with something of a "this is the point of no return" connotation, but at the time, it actually meant something much closer to "the game's afoot".
(Incidentally, just for background info, the reason that Julius Caesar crossing the Rubicon was so significant was that back in the day, it was forbidden for Roman generals to bring their troops into home territory of the Republic. After all, Rome was just that - a Republic. By effectively declaring war on the Republic, Julius Caesar would either end up dead or Emperor. Thus the connotation for crossing the Rubicon being a point of no return.)
The fact that back in 49 BC Julius Caesar was standing on a boat
|I imagine it looked like this|
I have all the photoshop skills of a blue whale so I cannot actually make this happen for you, but basically just imagine this guy:
in this hat: