The Bellum Gallicum, composed of eight books, is Julius Caesar’s account of his campaigns in Gaul from 58 to 52 BCE, with the eighth and final book added by Aulus Hirtius for the years 51-50 BCE. Its contents may be summarized as follows:
Book 1 (58): Caesar begins with a geographical outline of Gaul and moves on to describe battles against the Helvetii and the Germans. Aggression against the Helvetii is justified in terms of the potential – rather than actual – danger they pose to Roman territory. Aggression against the Germans is presented as being neither premeditated nor self-interested: it arises in response to constant Gallic appeals and arrogance on the part of the German king Ariovistus.
Book 2 …
Stevenson, Thomas Reginald. "Commentarii de Bello Gallico". The Literary Encyclopedia. First published 09 July 2009
[https://www.litencyc.com/php/sworks.php?rec=true&UID=25863, accessed 20 October 2017.]