|Caesar at the Rubicon by Wilhelm Trübner, 1880.|
How often any fond dog owner has seen this acted out! Certainly I have, most recently when the Christmas cookies were all on the sideboard and Jeeves, our male Boxer, had his eye out for opportunity!
I have seen the phrase about crossing the Rubicon before but never really knew what it meant. There's a whole article on it at Wikipedia, of course! So for anyone else who wonders, now we know.
Julius Caesar's crossing the Rubicon river on 10 January, 49 BC precipitated the Roman Civil War, which ultimately led to Caesar's becoming dictator for life (dictator perpetuo) and the rise of the imperial era of Rome. Caesar had been appointed to a governorship over a region that ranged from southern Gaul to Illyricum (but not Italy). As his term of governorship ended, the Roman Senate ordered Caesar to disband his army and return to Rome. He was explicitly ordered not to take his army across the Rubicon river, which was at that time a northern boundary of Italy. In January 49 BC, Caesar brought the 13th legion across the river, which the Roman government considered insurrection, treason, and a declaration of war on the Roman Senate. According to some authors, he uttered the phrase alea iacta est—the die is cast—as his army marched through the shallow river.
Today, the phrase crossing the Rubicon is a metaphor that means to pass a point of no return.