While it may seem to be a trivial geographical barrier, when Julius Caesar crossed the Rubicon with his army in A.D. 49, he effectively changed the course of history.

This is Latin for the famous and oft-quoted phrase, “The die is cast.” Or, at least, it is presumed to be. In actuality, the word iacta is in the nominative singular tense, which means the actual phrase is “The dice is cast,” which, while more accurate, doesn't quite roll off the tongue as well as the mistaken translation, so for the purpose of aesthetics, it's probably best to let sleeping dogs lie for now and get on with the point.

It is this Latin phrase which, according to Roman historian Suetonius (A.D. ~69 - ~130), Julius Caesar coined while leading a legion of troops across the Rubicon River in 49 B.C., an event which shaped the modern world as we know it in more ways than most people can probably imagine.

The Historical Context

Julius Caesar, who at this point was already about 51 years old, had been a very apt politician and Roman general for much of his life. He, had been elected military tribune after having been held prisoner by Cilician pirates, and in 69 B.C. elected Quaestor (an assistant to the consul – the highest position in Rome). In 63 B.C. Caesar was elected to the post of Pontifex Maximus – chief priest of the Roman religion.

Finally, in 59 B.C. Caesar was elected Roman Consul (provincial governor). While in office, Caesar was appointed governor of the province of Cisalpine Gaul (northern Italy), taking four legions into his territory after the end of his one-year consulship, Caesar proceeded to north, conquering much of western Europe in the name of the Roman Republic, eventually making it all the way to Briton (modern day England) before finally halting his progress.

In 50 B.C., his governorship having ended, Caesar was ordered back to Rome by the Roman Senate, led by Pompey. Due to a long standing law in Rome, Caesar would have to disband his legions prior to crossing the Rubicon, which ran north of Rome. No General was allowed to bring their armies any closer to Rome – such an act would be viewed as an act of war. It was this law which allowed the Romans to live peacefully with their neighbors.

The complicated story that follows can be summed up like this:

Having been refused any further consulship by the senate, and without a standing army by his side, Caesar feared that he would be tried as a criminal before the senate for his previous actions as consul (for he had demanded more power, in their eyes, than he should have been allowed, but was immune from prosecution by his title).

The Rubicon

It was at this point, camped with his army beside the Rubicon in 49 B.C. where Caesar decided that, “the die has been cast,” and that it was time to take action. So he marshaled his forces and brought them with him across the Rubicon as a sign of rebellion, then proceeded to lead them on an invasion of Italy and Rome into a great civil war. After claiming victory, Caesar was named “Dictator for Life,” and the Roman Empire (as history will always remember it) was born. It was the crossing of the Rubicon which opened the doors for Rome to expand and take over most of the known world within the next few centuries.

Modern Usage of the Historical Event

Today, when someone is said to have “crossed the Rubicon,” it means that they have crossed the point of no return, or have burned their bridges behind them. The die has been cast and there’s no turning back. When Caesar crossed the Rubicon, there was absolutely nothing he could due to turn back the clock; the war had begun.

Julius Caesar himself, the very first true Roman Emperor, had a legacy far greater than the vast majority of his successors, thanks to this little act of defiance. It was his action that turned Rome from a somewhat democratic Republic into a much more dictatorial Empire.

His own last name, Caesar, was given as a commemorative title to Emperors throughout the history of the Roman Empire, and the word became the etymological root for the names of other rulers such as the German Kaisar and the Russian Czar. His name became synonymous with ruling Empires, and it was his crossing of the Rubicon which made it all possible.

The Geography of the Rubicon

With its great historical importance, it is surely somewhat ironic that the actual Rubicon no longer exists. Its exact path, in fact, can no longer be found, though archaeologists for the most part think they know where it probably was. The problem is that over the years, especially as the river ceased to be the border of Rome as the empire spread out around it, the name was simply dropped from the lexicon somewhere along the way.

In addition, the area in which it once lay has flooded several times in history, changing the course of all the rivers in the area, and to make it even more difficult, the Italians have built many water projects in that area in order to prevent future flooding, which changed the locations of rivers yet again. So now it is difficult to know where the river was, exactly, except for what can be learned in ancient writings which described the land (though apparently not with much detail).

Still, the Rubicon lives on as one of the defining moments of western civilization as a whole, which will have to do for now.

References:

Holland, Tom. “Rubicon.” Anchor. 2005.

“Julius Caesar Crosses the Rubicon.”