Historical Analysis: Considerations on the Causes of the Greatness of the Romans and their Decline

Overview
Montesquieu’s 1734 historical analysis traces how Rome rose from a small city-state to a universal empire and why that very greatness precipitated decline. He links military success, civic virtue, and institutional design to expansion, then shows how conquest transformed manners, wealth, and power so profoundly that the republican framework could no longer hold. The narrative moves briskly from early kingship through the Republic’s struggles and victories to the civil wars and imperial monarchy, using examples to expose the interplay of laws, customs, and fortune in Roman fate.

Thesis and Method
The central claim is that political institutions and national character, more than individual rulers or accidents, shape the destiny of states. Rome’s greatness was not a miracle of chance but an outcome of disciplined mores, austere habits, and a constitution that balanced competing forces. Decline followed when conquest-generated wealth, administrative scale, and military professionalization altered those foundations. Montesquieu’s method is causal and comparative, contrasting Rome with rivals like Carthage and examining how changes in laws and manners reconfigured incentives.

Foundations of Greatness
Early Roman virtue, frugality, severity of customs, and a citizen-militia forged by agrarian life, produced resilience and unity. The mixed constitution, with consuls, senate, and tribunes, fostered both vigor and restraint. The dictatorship, limited in duration, offered lawful energy in emergencies. A distinctive genius for alliance-building extended Rome’s reach: by granting varying degrees of citizenship and imposing cleverly graded obligations, Rome multiplied its manpower while keeping control. This combination of civic hardiness, legal prudence, and calibrated inclusion explains steady victory over neighboring peoples and, later, over the great Mediterranean powers.

Expansion and Governance
Roman warfare was relentless but rational. They learned from defeat, waged long wars, and avoided catastrophic peace terms that would foreclose future advantage. Against Carthage, perseverance and strategic adaptation triumphed. In governing provinces, Rome built an empire of taxes and roads, sustained by senatorial oversight and magistrates, but also tempted by opportunities for extortion. The senate’s deliberative capacity, focused on long horizons, provided continuity. Yet success changed incentives: spoils flowed to the elite, political competition sharpened, and the old equality of citizens was eroded by wealth and patronage.

Dynamics of Decline
The sources of strength became sources of weakness. Conquests created armies whose loyalty shifted from the state to generals dispensing plunder and promises. The professional soldier replaced the citizen-farmer, tilting power toward commanders like Marius, Sulla, Pompey, and Caesar. Vast fortunes and luxury softened mores; the struggle for offices turned violent; exceptional powers designed for emergencies became ordinary instruments of faction. Laws strained to manage the scale of empire, and constitutional balances that functioned in a city-state faltered in a world-state.

Empire and Aftermath
The imperial solution ended civil war but at the price of liberty. A military monarchy, dependent on the legions and the Praetorian Guard, was inherently unstable. Succession without fixed rules invited intrigue and murder; fiscal burdens mounted to maintain armies and court; the bureaucracy expanded and hardened. Provincial administration could be more orderly, but the civic spirit dimmed as political participation narrowed. External threats pressed on lengthening frontiers, yet the decisive fragilities were internal: overcentralization, fiscal oppression, and the erosion of the republican energy that had made domination possible.

Significance
The analysis offers a general lesson about growth and fragility. Institutions suited to acquisition are not always suited to conservation; the vastness produced by success demands different arrangements than those that created it. Rome’s story illustrates how laws, manners, and scale interact, how virtue can be unmade by victory, and how military dependence corrodes civil freedom. Without denying the role of chance, Montesquieu shows that political causes, not providence, explain the arc from austere city to unwieldy empire and the slow, structural nature of its decline.