They had a comparable military power, but unlike Rome their ultimate downfall was the tribal nature of their society, which sometimes caused rifts between various Gallic factions that Caesar was able to take advantage of. The Gauls were a formidable enemy for Caesar. Though Caesar claimed that overthrowing Gaul was a pre-emptive and defensive matter, which would secure the Romans against a comparable military force, many believed that Caesar was attempting to plunder to pay some debts, and that his real motivations were more to make a name for himself politically. McCullough goes into many of the details here, including the political landscape around Caesar's invasion of Gaul, which caused many more conservative Romans back home to question his motivations. The first half of the historical novel details the Gallic conquests, including the notable uprising of the Gauls at the hand of Vercingetorix, the Gallic leader who attempted to unite the Gallic tribes to defeat Caesar. When the novel opens, Caesar has just invaded Britannia, and is preparing to take control. The novel begins in 54 BC, with Caesar's Gallic conquests.

McCullough's focus is on the political and military details of this narrative, with some humanizing elements, particularly in terms of Caesar's grief and a fictional romance. Because the book is based on the accounts of Caesar himself and his comrades, McCullough's story follows closely to the actual narrative of events from 54 BC to 48 BC, when Caesar fought Pompey the Great for control of Rome. Caesar by Colleen McCullough is a historical novel and the fifth book in McCullough's Masters of Rome series, which explores the fall of the Roman Empire.

Colleen mccullough cesar