Rome's imperialism allowed it to gather booty and slaves, essential for the functioning of its economy. But the subduing of huge areas of the continent also allowed it to create areas with which trade was possible. Caesar was mostly concerned with making sure that the local tribes could not damage Rome's economic interests. So some of the book is accounts of Caesar's attempts to create alliances between Rome and various French and Germany tribes. It's fascinating to see how divide and rule is used to undermine the power of the united tribes.
But most of the book is a military account. In places it's breathless as thousands of Roman soldiers and their mercenary allies (often German cavalry) smashes the numerically superior tribes. Sections of the book contain detailed accounts of contemporary warfare. The description of the Siege of Alesia, where the Roman area besieged a town held by the Arveni tribe under the leadership of Vercingetorix. The Roman's completely surrounded the town and held off a huge relief force before winning a military victory that is probably still looked at in academies today.
But what really struck me about reading this book is how it exposes Roman occupation and military action as essentially terror. Hostages are demanded, villages and towns are razed. People are killed in huge numbers when they aren't captured into slavery. Crops are despoiled or stolen to keep the legions marching and the enemies aren't simply defeated, they are smashed.
Setting out once more to harass the Eburones, Caesar sent out in all directions a large force of cavalry that he had collected from the neighbouring tribes. Every village and every building they saw was set on fire; all over the country the cattle were either slaughtered or driven off as booty; and the crops, a part of which had already been laid flat by the autumnal rains, were consumed by the great numbers of horses and men. It seemed certain, therefore, that even if some of the inhabitants had escaped for the moment by hiding, they must die of starvation after the retirement of the troops.Caesar here is writing about himself in the third person, so this is his own account of events. This sort of mass terror is repeated time and again by the Romans and their allies. What is also remarkable about these descriptions is that they were intended to be read as a celebration and justification of Caesar's actions. In other words, they were read and accepted by the Roman population, who presumably didn't object - or if they did we have no record of it. Certainly Caesar saw no problem in putting his mass oppression in print.
For those interested in military history this is a great read. For those who want to understand the reality of Imperial rule there's also much in it. Sadly the parallel with more recent imperial behaviour is all too clear.
Harper - The Fate of Rome
Beard - SPQR
Suetonius - The Twelve Caesars
Tacitus - The Annals of Imperial Rome
Plutarch - The Fall of the Roman Republic
Parenti - The Assassination of Julius Caesar