«Ἀνερρίφθω κύβος» (anerriphtho kybos, lit. Let the die be cast) was attributed by Suetonius to Caesar when it was reported that some legionaries cross the Rubicon. Why did Caesar move to the Rubicon and stop there? Was it because after that, a civil war would be unavoidable and Caesar wanted to avoid it? Was it just an excuse to start the war anyway?
The Rubicon river marked the boundary between the province of Cisalpine Gaul and Italy proper. Caesar, as a proconsul, held imperium (the right to command) within the provinces, but only a consul or praetor could hold imperium inside Italy. Generals were expected to lay down their command and re-enter Italy as private citizens; not doing so would be seen as a threat to Rome. According to Wikipedia,
"Suetonius's account depicts Caesar as undecided as he approached the river, and attributes the crossing to a supernatural apparition",
suggesting that he was unsure whether to provoke civil war at that time.
His act of crossing the Rubicon leading fully armed soldiers immediately created a force in Italy in opposition to the Senate; thus, a civil war had begun.
Wikipedia has a much more detailed (and better cited!) section on this very subject.
Why Caesar crossed the Rubicon is a question none other than Caesar himself answered:
'They wanted it so. I, Gaius Caesar, in spite of such great deeds would have been condemned, had I not sought help from my army (hoc uoluerunt. tantis rebus gestis C. Caesar condemnatus essem nisi ab exercitu auxilium petissem).'
(Suet. Dl 30.4; Plut. Caes. 46.1. )
That alludes to his successes on the one hand and his not only potentially dire legal situation.
He made enemies, a lot of enemies, in the years leading up to this situation. But his actions of interior policy as consul in 59 went unpunished, in fact unpunishable, since he was holding office, or imperium.
He was faced with laying down arms and office to return to Rome and hold a triumph, but face a trial for misdeeds afterwards. To avoid that he wanted the consulship for 48. North of the Rubico he had immunity, legal protection for holding imperium, that is command over the legions in Gallia, and the resulting immunity from that he alsocould enforce himself with military might if need be.
Normally, he would have stand election for consulship in person, opening up all the legal pitfalls of being a private citizens without an army. His solution to that was trying to get elected to the position without being present. A clever move not unprecedented, as Pompeius was elected in absentia before. But allowing Caesar that would not only give him power again to behave in the same manner against the wishes of the optimates like he did in his first consulship. It would have also been the de facto submission of his enemies, equalling a public statement of 'no prosecution and no accusation' for his prior 'misdeeds'.
For Caesar it was either holding office – any high office – or face complete downfall. Seeing the distribution of troops and commanders within Italy it was also the opportunity for action.
At the beginning of the year 49 Caesar sent a letter in which he presented the old demands: he would either be entitled to apply for the consulate in absentia, or all troop commanders would have to be recalled. The Consul Lucius Cornelius Lentulus Crus did not even mention this. Instead, Caesar was now to be given a deadline by which to dismiss his army, otherwise he would be treated as a traitor.
Now Caesar's tribune interceded; negotiations were still feverish behind the scenes, and Caesar even allowed himself to be negotiated down to Illyricum and only one legion, to which Pompeius, but not Cato, wanted to respond.
This was the 'compromise' offered by Caesar as a way out of the stalemate situation in the Senate. But Caesar's proposal was not accepted and Antonius and Cassius blocked every other advance by their veto. Only the declaration of a state of emergency remained, with which Pompeius and other office holders were authorized to appropriate measures for the protection of the state. Antonius and Cassius, whose protection of immunity was precarious in a state of emergency, fled to Caesar, who was now able to write the defence of the people's tribune and thus of the people's rights of freedom on his flags.
For these reasons every thing was done in a hasty and disorderly manner, and neither was time given to Caesar's relations to inform him [of the state of affairs] nor liberty to the tribunes of the people to deprecate their own danger, nor even to retain the last privilege, which Sylla had left them, the interposing their authority; but on the seventh day they were obliged to think of their own safety, which the most turbulent tribunes of the people were not accustomed to attend to, nor to fear being called to an account for their actions, till the eighth month. Recourse is had to that extreme and final decree of the senate (which was never resorted to even by daring proposers except when the city was in danger of being set on fire, or when the public safety was despaired of). "That the consuls, praetors, tribunes of the people, and proconsuls in the city, should take care that the state received no injury." These decrees are dated the eighth day before the ides of January; therefore, in the first five days, on which the senate could meet, from the day on which Lentulus entered into his consulate, the two days of election excepted, the severest and most virulent decrees were passed against Caesar's government, and against those most illustrious characters, the tribunes of the people. The latter immediately made their escape from the city, and withdrew to Caesar, who was then at Ravenna, awaiting an answer to his moderate demands; [to see] if matters could be brought to a peaceful termination by any equitable act on the part of his enemies.
–– Julius Caesar: "The Civil Wars", translated by W. A. McDevitte and W. S. Bohn
The consequence for this was clear: on 10 January 49 he crossed the Rubico, the border river between his province Gallia Cisalpina and Italy, and thus opened the civil war.
In defending his invasion of Italy to Lentulus Spinther, Caesar claims that one of the reasons he came out of his province was to assert the freedom of himself and the Roman people, who had been overwhelmed by the faction of the optimates; oppressum, though singular, surely qualifies se as well as populum Romanum (1.22.5). Indeed, Caelius reported in August 50 that Caesar was convinced that he could not survive (saluum esse, ap. Cic. Fam. 8.14.2) if he left his army; the reference must be to Caesar's political future. If, however, motivated by this political powerlessness, Caesar invaded Italy, it was imperative that he regularise his position as quickly as possible. Hence his (largely unsuccessful) efforts to persuade leading senators to remain in or return to Rome. An earlier action that showed Caesar's political weakness was the crossing of the Rubicon itself. It had been planned for some months. It revealed that Caesar was desperate to avoid prosecution. He had no remedy for the predicament he had created by his use of violence when consul in 59 apart from the further use of violence.
–– GR Stanton: "Why Did Caesar Cross the Rubicon?", Historia: Zeitschrift für Alte Geschichte, Bd. 52, H. 1, 2003, pp. 67-94. (jstor)
At the Rubico he reached the boundary for his imperium geographically and he reached the limits of his office term at the same time. He marched on Rome – as far as legal limits allowed and near enough to show force as well as at least feigning to be ready to compromise. His very brief stay at the river was stopping at barking but not biting, yet.
Why was Caesar at the Rubicon?
The perception was Caesar was at the Rubicon, with a single legion (1/10th of his available forces) to seek terms in his confrontation with his political rivals who controlled the Senate. That Caesar subsequently crossed the Rubicon, invading Rome reluctantly only after his moderate requirements for peace were refused. Another popular belief is that Caesar was at the Rubicon to pursue his life long ambition to invade and conquer Rome by force and that all his posturing and offering terms were a façade to make him appear weak in order to goad and embolden his political enemies to fool hardy action. Caesar wanted to be seen as being reluctant and forced to invade rather than be seen as the aggressor.
The first Triumvirate beginning in 60BC was an informal alliance between three great men of Rome. These men did not agree on political issues but rather agreed to support each other as each worked for his own benefit. The three men were:
- Gnaeus Pompeius Magnus, Romes greatest war hero and general, (up to that point).
- Marcus Licinius Crassus, Rome's richest citizen.
- Gaius Julius Caesar, who was politically popular on the basis of his family's name, political support for popular reforms, and his office. Caesar at the time of the forming of this alliance was the chief priest of Rome (Pontifex Maximus) which gave him significant political influence. Caesar though was perceived to be the weakest of the three great men when the triumvirate was formed.
Through the triumvirate alliance Pompeius remained in Rome solidifying his power and Crassus and Caesar would leave Rome to seek military fame and wealth as governors of remote unruly provinces. Crasus in Syria and Caesar in Gaul.
The First Triumvirate
Caesar was at the time very well connected with the Populares faction, which pushed for social reforms. He was moreover Pontifex Maximus—the chief priest in the Roman religion—and could significantly influence politics, notably through the interpretation of the auspices. Pompey was the greatest military leader of the time, having notably won the wars against Sertorius (80–72 BC), Mithridates (73–63 BC), and the Cilician Pirates (66 BC). Although he won the war against Spartacus (73–71 BC), Crassus was mostly known for his fabulous wealth, which he acquired through intense land speculation.
Through this alliance Caesar acquired wealth and greatly enhanced his fame and military reputation as Governor of Gaul. Their alliance ended, when Marcus Crassus was killed in 53 BC.
- Plutarch thought that fear of Crassus had led Pompey and Caesar to be decent to each other and his death paved the way for the subsequent friction between these two men and the events that eventually led to civil war.
- Florus wrote: "Caesar's power now inspired the envy of Pompey, while Pompey's eminence was offensive to Caesar; Pompey could not brook an equal or Caesar a superior.
- Seneca wrote that with regard to Caesar, Pompey "would ill endure that anyone besides himself should become a great power in the state, and one who was likely to place a check upon his advancement, which he had regarded as onerous even when each gained by the other's rise:
In 50 BC Cesar's former ally Pompey was now allied with the Roman Senate. They conspired to strip Caesar of his political immunity as governor of Gaul, prosecute him for "insubordination and treason". Governors of Roman provinces gained wealth by extortion and bootie from conquests. Caesar had not restricted his "franchise" to Gaul but had also raided into neighboring provinces. An offense his political enemies now wished to use against him.
They hoped to strip him of his office and immunity, force him to accept banishment for some period of time. The Senate and Pompey hoped the scandal and subsequent disgrace would weaken Caesar politically.
Crossing the Rubicon by a Roman Army was an act of aggression against Rome. Roman armies were raised and maintained by personal fortunes and benefited greatly financially from having successful aggressive leaders like Caesar. Thus their loyalty was to their commanders and not to the state / Rome. Caesars motivation for crossing the Rubicon, and invading Rome was perceived to be a response to the aggressive actions by the Senate and his former ally Pompey but their is another school of thought which proposes an alternative view. That Ceasar was a supremely ambitious guy, who saw himself in direct competition with Alexander the Great from a young age as the greatest conquer in history. That he always desired to invade and conquer Rome and that he was savvy enough politically to make it appear to be his opponents fault.
Pompey received false reports that Caesar's troops were not loyal to him, and wished to support Pompey in his confrontation with Caesar. Reports which emboldened Pompey. Caesar also crossed the alps with but a single legion, his 13th Legion (6000 men) a relatively small force. Caesar had been granted command of 4 legions when he left for Gaul and the historian Livius says had 10 legions at his command in Gaul. Bringing only a single legion makes him appear weak and unprepared confrontation.
Prior to crossing the Rubicon Caesar offered terms to the senate. Caesar offered to disband his legions and retain only two legions if offered governorship of the province of Illyricum. Later he reduced his requirements to only a single legion. If granted this position it would give him immunity from prosecution from his enemies and give him time to use his popularity and fortune to run for console. Makes Ceasar appear to prefer a political outcome rather than a military one.
In part because of the perception of Ceasar's weakness, the Senate over reached. It declared the popular Caesar an enemy of the state, and seemingly forced his hand to invade Rome. The Senate and Pompey believed evidently weak Caesar would not cross the Rubicon with a single legion giving Pompey time raise forces to oppose him. Caesar however; attacked and his single legion of veterans from Gaul proved more than a match for Pompey's forces.
LangLangC But why 'schools', who are prominent members of these schools? (That also means: imo the 'Caesar mastermind' 'pole' is not impossible and offers a few interesting details & alternatives, but seems a rather unlikely variant in all these details. Too many variables, too long game…)
You are not wrong. There is debate about Caesar's motivation in seeking peace. As I said two schools of thought. I believe the more supported belief by historians is Caesar invited Pompey's and the Senate's aggression. Making himself appear weak, reasonable and vulnerable to provoke them into conflict in which he was perceived to be their victim. This theme was first proposed by the Roman historian Suetonius in his Twelve Caesars and has widely held by historians. It was opposed by the respected historian Theodor Mommsen.
The machinations and as you say, "long game" is why Julius Caesar goes down as not just one of the greatest military leaders of all time, but one of the greatest political strategists too.
Caesar's Sincerity in Negotiating for Peace
Given the fact that Caesar did make a number of attempts to negotiate a peaceful compromise with Pompey and the Senate both prior to and after the crossing of the Rubicon, it must now be determined whether these offers were indeed sincere. It has been observed that, before Mommsen, the great majority of historians accepted the opinion reported by Suetonius that Caesar had been determined to seek supreme power by force since his youth38. As such some historians - like Hardy - believed that Caesar's peace offers were made because «he knew that they would be refused. In other words, such offers were made for the purpose of deceiving public opinion and of creating disunity in the ranks of his opponents. Other historians - such as Schmidt - cited a letter by Cicero and were convinced that Caesar's various offers of peace were merely a ruse in so far as they were apt to delay military action on the part of his opponents. Mommsen, however, challenged these views by contending that all of Caesar's proposals were sincere and that it was only the folly and obstinacy of his opponents which made them reject these offers and so made a war to the bitter end inevitable. He was in turn supported by such historians as Meyer, Syme and Adcock. As can be seen, three different alternatives exist