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Ancient Rome · 52 BC

Was Caesar’s Gallic War a war of aggression?

The seminar question: “Was Caesar’s Gallic War aggressive, and how did Romans judge it?”

Julius Caesar used his command in Gaul from 58 BC to gather wealth, prestige and a devoted army, defeating Vercingetorix’s coalition at Alesia in 52 BC. Ordered to give up his command, he crossed the Rubicon on 10 January 49 BC and began a civil war, which his veterans won at Pharsalus in 48 BC.

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Map of Julius Caesar and the civil war (52 Bc)
52 BC · THE RISE AND FALL OF ROME, 264 BC – AD 476

In 58 BC Caesar needed a success large enough to answer his debts and match the prestige Pompey had won in the east. His governorship in Gaul gave him the means to seek it. The peoples of Gaul were divided by their own quarrels, and he could enter a dispute as an ally, then present further campaigns as defense or prevention. Much of the conquest was a war of choice. His Commentaries, written in a plain and persuasive style for Roman readers, gave his own account of those choices.

The short answer

THE TURNING POINT

The Rubicon, 10 January 49 BC. The Rubicon was a small stream marking a provincial boundary; its exact course is still disputed. Caesar crossed it with his legion on 10 January 49 BC. Ancient accounts have him pause on the bank and quote a favorite playwright. The decision behind the scene was stark: surrender his command and face prosecution and exile, or lead soldiers across the boundary in defiance of the Senate. He chose the latter, beginning civil war. The phrase “crossing the Rubicon” came to mean an irrevocable decision.

What it changed

Gaul: a province that changes the empire’s shape. After eight years of conquest, Gaul became part of a Roman world that lasted there for roughly four centuries. Lyon served as an administrative hub; Roman cities, villas and Latin culture shaped the province, and Latin became an ancestor of French. The frontier lay at the Rhine rather than the Alps, with Germania Magna beyond it. Chapter 6 follows Rome’s efforts to establish that boundary.

The dictatorship shows its face too soon. The calendar, colonies, debt and citizenship for Cisalpine Gaul were problems on which Caesar could act rapidly. His dictatorship also made the difficulty of concentrated power visible: force and favor supported his position, his safety depended on that power, and no succession was established. His eighteen-year-old heir Octavian would later keep decisive authority while carefully presenting republican forms.

The assassins prove the assassination pointless. Removing Caesar did not remove the conditions that had enabled his rule. Within twenty months new proscriptions claimed Cicero, and his head was displayed on the speaker’s platform. Another civil war followed within three years, and a new monarch within seventeen. From 44 to 31 BC Rome continued to live with the consequences of the Republic’s breakdown.

The full answer, argued

Caesar described his campaigns as defense of allies or prevention of danger, but intervention also opened the way to further conquest. Roman judgments differed. Cato reportedly urged the Senate to surrender Caesar to the Germans for killing the Usipetes and Tencteri during a truce, applying Roman standards to his conduct. The Senate also voted extraordinary thanksgivings, and the assemblies welcomed his victories. Glory and plunder won support despite objections. The expansion of Roman power and the immense suffering it caused are both part of the war’s history.

An interesting fact

The Roman calendar had drifted months out of season, partly because the priests who managed its adjustments could use them for political convenience. In 46 BC Caesar, advised by the Alexandrian astronomer Sosigenes, brought it back into alignment by making that year 445 days long. Romans called it the “year of confusion.” His replacement averaged 365¼ days a year; the Gregorian reform of 1582 corrected an error of about eleven minutes annually. July, Caesar’s birth month, was named for Julius Caesar in 44 BC.

This is the study layer of Julius Caesar and the civil war, chapter 5 of The Rise and Fall of Rome, 264 BC – AD 476; the full index of the atlas is here.

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