After the death of Crassus in 53 BC Carre it was progressively cracks in the political alliance with Pompey the Great who gave expression to the conservative tendencies of the Senate by opposing the work of Caesar in Gaul. Despite mediation efforts by both sides, it was impossible to reach a compromise solution, and on January 10, 49 BC Caesar crossed the Rubicon River in arms, the river that marked the boundary within which it was illegal in a general marched in arms. It was a real act of war against the Republic of Caesar: the nobles gathered around Pompey who left Italy to transfer his forces in the Balkan Peninsula. Cesare, assured himself control of Rome and later defeats the Pompeian forces in Spain, reached the shores of the rival Albania, where he was defeated at Dyrrhachium; the two armies clashed then again in August 48 BC, at Pharsalus in Thessaly, where Caesar gained the decisive victory over his rival. The final defeat of the Pompeian faction procured unto Caesar the antipathy of many of the supporters of the Republic, who feared the establishment of a regime to monarchical character, that would have been hated by all the Romans. But also trends in authoritarian power of Caesar, the continuation of the civil wars, the pressures of the groups anticesariani internal to the Senate and the rivalries between the same components of the environment Caesarian created a favorable situation for the development of projects of conspiracy that had to be resolved with the killing of the dictator. Moreover, the plot seemed the rest easy, as Caesar, considering themselves untouchable after the victory in the civil war against Pompey and after the Senate had sworn to protect, had dismissed the two thousand Hispanics of his personal guard. Adherents to the conspiracy and supporters were sixty while cesaricidi real were no more than twenty, all magistrates or senators, except for a consular, and stabbed 23 times Caesar, who, according to historical tradition, died at the foot of the statue of his old enemy, Pompey the Great. Among cesaricidi include the famous Brutus (Marcus Junius Brutus, son of Servilia Caepionis, lover of Caesar) and Cassius (Cassius Longinus, who had managed to survive the defeat of Carre and was later to become one of the officers of Pompey at Pharsalus) .

Caesar's death, however, did nothing to stop the irreversible process of the end of the Republic. The death of the dictator in fact triggered a series of events that led to the emergence of Octavian, Caesar's adopted son and heir, who after fighting a civil war against Mark Antony (who had been a close associate of the late dictator), ended the Republic and established the Principality.
And then, on January 16, 27 BC was elected first Emperor of Rome with the title of Augustus.