Gaius Julius Caesar' (, July 100 BC – 15 March 44 BC) was a Roman general, statesman, Consul, and notable author of Latin prose. He played a critical role in the events that led to the demise of the Roman Republic and the rise of the Roman Empire. In 60 BC, Caesar, Crassus, and Pompey formed a political alliance that was to dominate Roman politics for several years. Their attempts to amass power through populist tactics were opposed by the conservative ruling class within the Roman Senate, among them Cato the Younger with the frequent support of Cicero. Caesar's conquest of Gaul, completed by 51 BC, extended Rome's territory to the English Channel and the Rhine. Caesar became the first Roman general to cross both when he built a bridge across the Rhine and conducted the first invasion of Britain.
These achievements granted him unmatched military power and threatened to eclipse the standing of Pompey, who had realigned himself with the Senate after the death of Crassus in 53 BC. With the Gallic Wars concluded, the Senate ordered Caesar to lay down his military command and return to Rome. Caesar refused, and marked his defiance in 49 BC by crossing the Rubicon with a legion, leaving his province and illegally entering Roman territory under arms. Civil war resulted, from which he emerged as the unrivaled leader of Rome.