What it is
The Commentarii de Bello Gallico — the "notes on the Gallic war" — is Caesar's first-person account of the nine years during which he extended Roman authority across what is now France, Belgium, the Low Countries, the Rhineland and (briefly) across the Channel into Britain. The work runs to seven books, one per campaigning year, plus an eighth book added by Caesar's officer Aulus Hirtius after his death to bring the narrative down to the outbreak of the civil war. Caesar's parallel work on that war, De Bello Civili, is preserved separately. He refers to himself in the third person throughout — Caesar misit, "Caesar sent" — a literary device which lent the text the appearance of dispassionate report.
Historical context
Caesar's command in Gaul was an extraordinary commission, granted under the lex Vatinia of 59 and extended by the conference at Luca in 56. It ran for nine years — far longer than the regular term — and the politics in Rome that allowed it to continue depended on Caesar's ability to maintain his standing with the Roman public. The Commentarii were a deliberate instrument of that politics. Books were dispatched to Rome each winter, circulated in manuscript, read aloud and discussed; the cumulative effect was that the Roman political class read Caesar's account of his own war as it happened. The work is propaganda in the literal Latin sense — it propagated a particular account — without being crude propaganda. The prose is famously plain, the events specific, the case implicit.
What it argues
The argument it makes is at once military and political. Militarily, it presents Caesar as the disciplined commander of a disciplined army — making the calls on the day, sharing the privations, knowing every cohort by name. Politically, it presents the Gallic command as a service to the Republic: the Helvetian migration of 58 (Book I) is framed as a threat that had to be met; the Germanic intrusions across the Rhine (Books I, IV, VI) are framed as the long threat against which Rome's frontier had to be held; the Belgic campaigns (Book II) and the British expeditions (Books IV–V) are framed as the extensions of a coherent strategic responsibility. The ethnographic excurses on the Gauls (Book VI) and the Germans (Books IV, VI) — much-quoted in early-modern Europe as the principal classical description of the Northern peoples — sit inside the argument: a Rome that does not understand its frontier cannot defend it.
What the Commentarii do not say openly is also part of the work. They do not acknowledge that the army Caesar is describing has, by the standards of the mos maiorum, become an army whose primary loyalty is to him rather than to the city. The reader who came to the text after 49 BCE could not miss the point.
Why it has been read
Two reasons, each independent. As Latin prose, the Commentarii are the model of the genus tenue, the plain style — clear, fast, economical, taught for two thousand years to beginning Latinists as the readable starting point. As a manual of war, they were studied by Vegetius in antiquity, by Maurice of Nassau during the Dutch revolt, by Frederick the Great, by Napoleon, and by the modern Anglo-American academies of military history. The combination — that the text is at once an exemplary literary work and an exemplary military document by a commander whose political career ended a republic — makes it unusual in the European canon.
Citing the Bello Gallico
Standard citation is by book and chapter (e.g. BG 1.1 — the famous opening, Gallia est omnis divisa in partes tres). The standard Latin text is Renatus du Pontet's Oxford Classical Texts edition; see our Sources page.