The municipal comitia curiata ceased to be politically effective first under the military despotism of foreign rulers and then by reason of the expansion of the state till it included an area of nearly a thousand square kilometres. From that time forward the tribus became the basis of all political organisation, and remained so to the end.
But the army thus reorganised was a two-edged weapon. The tyrannical license of the last Tarquin roused the love of liberty in the breasts of the Romans. The army renounced its allegiance; through years of conflict and in sanguinary battles Rome, and all Latium with her, won back its independence of foreign Tuscan rulers.
The wars waged by Rome in the century after the expulsion of the kings are hardly worthy to be recorded on the roll of history. After valiantly repulsing the Etruscan commanders who endeavoured to restore Tarquin (496 B.C., battle of Lake Regillus), Rome entered into a permanent alliance with the Latin confederacy, an alliance that was not only strong enough to protect her against the constant attacks of mountain tribes (Æquians and Sabines on the northeast and Volscians on the southeast) but enabled her gradually to push forwards and conquer the south Etruscan cities of Veii and Fidenæ. Fidenæ fell in the year 428 B.C., Veii the emporium of southern Etruria, was reduced in 396, after a siege of ten years’ duration.
An attempt to intermeddle in the affairs of northern Etruria resulted in a catastrophe that threatened Rome with final annihilation. Some time earlier hordes of Gauls had penetrated into northern Italy through the passes of the Alps. At the beginning of the fourth century B.C. the Senonian Gauls effected a permanent settlement in the valley of the Po and from thence invaded Etruria. When they attacked Clusium (Chiusi) in middle Etruria the Romans made an attempt at diplomatic intervention, but only succeeded in diverting the wrath of the enemy to themselves. The Gauls made a rapid advance, succeeded in routing the Roman forces at the little river Allia, only a few miles from Rome, and occupied the city itself. The citadel alone held out, but more than six months elapsed before the flood of barbarians subsided, and Rome was forced to purchase peace by humiliating concessions.
Rome arose after her fall with an energy that commands admiration, and she had soon won a position in middle Italy more important than that which she had held before the Gallic invasion. By partitioning southern Etruria among Roman citizens and founding colonies which at the same time served as fortresses and substantial bases for the advance of the Roman army she became a power of such consequence that she not only compelled the Æquians and Volscians by degrees to acknowledge her suzerainty but was able to assume the offensive in middle Etruria and the land of the Sabines.
When the Senonian Gauls returned to the attack, as they did two or three times a generation later (360, 349, and 330 B.C.), they found themselves confronted by the forces of the Latin league in such numbers that they declined to join issue in a pitched battle, presently retreated, and finally concluded a truce for thirty years (329-299 B.C.).
The increased strength of the Roman community within its own borders after the catastrophe of the Gauls is vouched for by the multiplication of municipal districts in spite of heavy losses in the field, the number and importance of the colonies, the gradual expansion of commerce and augmentation of the mercantile marine, the introduction of coined money (about 360 B.C.) in place of the clumsy bars of copper, and lastly, the increasingly active relations of Rome with foreign powers. About the year 360 B.C. the Romans sent votive offerings to Delphi, and made efforts both before and after to introduce Greek cults into their own country. But the strongest evidence of the extension of Roman trade and the esteem in which Rome was held as the contract-making capital of the commercial cities of middle Italy is furnished by her treaties with Carthage (probably 348 and 343 B.C.). The provisions (the text of which has come down to us) that Roman vessels should not sail westwards beyond a certain line in north Africa or in Spain, prove conclusively that the Carthaginians thought Italico-Roman competition a thing worth taking into account.
The internal development of the Roman state during this period (509-367 B.C.) is a matter of greater moment than many wars and military successes. The constitutional struggles which took place in an inland town in Italy are in themselves of small account in the history of the world. But the forms into which civil life and civil law were cast in Rome were subsequently (though in a much modified form) of great consequence to the whole Roman Empire. The division into curiæ obtained not only in Rome itself but in the remotest colonies of the empire in its day. The tribus, i.e., the districts occupied by Roman citizens enjoying full civil rights, afterward included all the citizens of the empire. Moreover, a particular interest attaches to the history of civil and private law among the Romans from the fact that its evolution has exercised a controlling influence on the juridical systems of the most diverse civilised peoples to this day.
The legal and constitutional changes which took place at Rome during this period were rendered imperatively necessary (in spite of the conservative character of the Roman people) by the changed status of the city. During the earlier half of the monarchy all civil institutions had been arranged with an eye to municipal conditions. But the Rome of the Tarquins (in the sixth century B.C.) had hardly become the capital of a domain of nearly a thousand square kilometres before she found herself under the necessity of admitting her new citizens, first into the companies (centuriæ) of the army, and presently (after 509 B.C.) into the popular assemblies which voted by centuries. The old sacral ordinances, which were unsuited to any but municipal conditions, were superseded by the jus Quiritium, or Law of the Spearman, an ordinance of civil law.
It was no longer necessary to secure the assistance of the pontiff and the assent of the popular assembly voting by curiæ in order to make a will or regulate other points of family law. The civil testament and corresponding civil institutions took the place of the old system.
But the Roman state did not escape grievous internal troubles. After the expulsion of the kings the patrician aristocracy strove to get all power into their own hands. The senators were drawn exclusively from their ranks, civil and military office became the prerogative of a class. All priestly offices were occupied by members of patrician families. The patricians were supposed to be the only exponents of human and divine law. And it was an additional evil that the aristocratic comitia centuriata, which actually excluded the poorer citizens, were wholly deficient in initiative.
The Roman plebs suffered even more from the lack of legal security under an unwritten law arbitrarily administered by patrician judges than from the lack of political rights. In the famous bloodless revolution of 494 B.C. the plebs won the right of choosing guardians of their own, in the person of the tribunes of the people, who had the right of intervention even against the consuls, and soon gained a decisive influence in all public affairs. By decades of strife the hardy champions of civil liberty succeeded in securing first a written code of common law and then a share for the plebeians in public office and honours. From 443 B.C. onward there were special rating-officers (censors) independent of the consul, whose business it was to settle the place of individual citizens on the register of recruiting and citizenship, and to regulate taxation and public burdens.