[fluorocarbon]

Mortal Republic is not about the fall of Rome. It's about the fall of the Republic, or the transition from a republic (oligarchy) into an empire (monarchy). Rome in fact reached its largest extent about a hundred years after the fall of the Republic, under the emperor Trajan.

When people talk about "Rome's fall," they're usually referring to the decline of the western half of the empire which happened 400-500 years after the fall of the Republic. The reasons for this fall are debated, but it's likely due to some combination of plague, invasions, elite infighting, and a lack of rules about succession leading to constant civil wars.

[anigbrowl]

The GP didn't say it was about the fall of Rome, and nothing in the post suggests to me it was intended to be understood that way.

[aetherson]

I mean, his first sentence included the phrase "the story of Rome's fall" and nothing between there and the book suggested he'd changed topics.

[anigbrowl]

Given that he concluded with the focus on saving the republic specifically rather than Roman civilization it seemed obvious to me.