Quick questions on Caesar's conquest of Gaul, 58-50 BC: HSC Ancient History

Over the winter of 54-53 BC the Eburones, led by Ambiorix, destroyed an entire Roman legion and five cohorts under the legate Sabinus after luring them from their camp with false promises of safe passage - one of the few outright Roman disasters the Commentarii record. Caesar spent much of 53 BC, including a second Rhine crossing, on punitive campaigns to restore control before the far larger crisis of 52 BC.

Encouraged by political unrest at Rome, the young Arvernian noble Vercingetorix united a coalition of Gallic tribes in a general revolt in 52 BC. He adopted a scorched-earth strategy, burning towns and stores to starve Caesar's legions of supplies, though the Bituriges persuaded him to make an exception for the strongly fortified town of Avaricum (Bourges). Caesar besieged and stormed Avaricum, and the Commentarii record the population massacred almost to the last person - proving Vercingetorix's original judgement right and hardening Gallic resolve. Caesar was then repulsed with real losses at Gergovia, one of the few defeats the Commentarii openly admit.

Vercingetorix withdrew his forces into the hilltop oppidum of Alesia (in the territory of the Mandubii). Caesar responded with one of the most famous feats of ancient siege engineering: a double line of fortifications, an inner line of contravallation (about 16 km) facing the town to trap the defenders, and an outer line of circumvallation (about 21 km) facing outward against an approaching Gallic relief force, with Caesar's legions encamped in the corridor between the two lines. When the relief army arrived, Vercingetorix's Gauls attacked from within at the same moment as the relief force attacked from without; Caesar's forces, including Germanic cavalry allies, held both lines and broke the relief army in a decisive cavalry action. Vercingetorix surrendered soon after.

The Commentarii de Bello Gallico is both the single most important surviving source for the conquest of Gaul and a carefully constructed work of political self-promotion, and the two facts cannot be separated.

Caesar wrote Books 1-7, covering 58-52 BC, himself; Book 8, covering 51-50 BC, was added after his death by his legate Aulus Hirtius. The whole work is written in the third person ("Caesar ordered...", never "I ordered..."), a device that gives the narrative a false appearance of an impartial outside report even though its author is its central hero.

Because almost no independent Gallic written record survives, and because later ancient writers (Plutarch, Suetonius, Cassius Dio) drew heavily on Caesar's own account, the Commentarii dominate what is known about the war's course, chronology and tactics, including details later corroborated by archaeology, such as the fortifications at Alesia confirmed by nineteenth-century excavation at Alise-Sainte-Reine.

The Commentarii were composed and, on the standard view, circulated at Rome close to the events they describe, keeping Caesar's name and achievements before the Senate and public while he was absent from the city for nine years. Ancient writers preserve casualty tallies attributed to Caesar's own reckoning of the war - commonly summarised as around a million Gauls killed and a million more enslaved - figures modern historians treat as inflated self-promotion rather than a reliable count, alongside smaller but equally suspicious precise figures within the text itself, such as the claim that only 500 of 60,000 Nervii fighting men survived the Sabis in 57 BC. The consistently defensive framing of every campaign (protecting allies, responding to provocation) similarly serves to present a war of choice as a war of necessity.