in ancient rome, marrying someone of another class was no matter for neighbourhood gossip: for some years it was, quite literally, illegal. the barrier between patricians and plebeians was not held up only by custom and prejudice, but by a written prohibition that denied legal validity to their unions. and the law that brought down that wall was born, as almost everything in the early republic was, not from the heart but from a trial of strength.
the prohibition appeared in the twelve tables themselves, the code the plebs had wrenched from the patricians at the cost of so much blood barely a few years earlier. modern reconstruction places it in the eleventh table, part of the body of law added in the year following the decemvirate: the absolute veto on conubium, legitimate marriage, between patricians and plebeians. the justification the patricians offered mingled religion and lineage. only they, they claimed, could correctly take the auspices and commune with the gods; to mix their blood with that of the plebs would defile that sacred privilege and offend heaven. but the rule protected no altar: it protected a patrimony. its real effect, far more earthbound, was to guarantee that patrician lands, offices and priesthoods went on being transmitted within a closed circle, with no enriched plebeian able to slip into it through marriage.
to mix the blood, they said, offended the gods; in truth, what they were protecting was their monopoly on power.
the patricians’ calculation had an obvious weakness. rome lived in near-permanent war with her neighbours, and the bulk of the army was made up precisely of plebeians. in 445 bce, with fresh military threats on the horizon, the tribune of the plebs gaius canuleius found his lever. he brought forward a proposal to abolish the marriage prohibition, and the plebs backed him with its most effective weapon: refusal to enlist. without plebeian soldiers there was no army, and without an army the city stood defenceless. the senate, cornered between caste pride and the panic of invasion, gave way. the lex canuleia was passed, restoring conubium between the two classes and giving full validity to their marriages.
it would be naive to read this law as a romantic triumph. roman marriage had little to do with love: it was a contract between families, an instrument of alliance and the transmission of property. what the lex canuleia allowed was precisely that — that the great plebeian fortunes and the patrician names could be joined through marriage — and for that reason it benefited above all the rising plebeian elite, not the ruined day-labourer. it was no victory of sentiment, but a victory of class. even so, its political importance was enormous: it opened the first real crack in the wall that separated the two orders and marked the beginning of the slow process by which the plebs would, decade after decade, gain access to the magistracies, the priesthoods and the consulship.
the same agitation of that year yielded a second conquest, less famous but more cutting for the patricians. canuleius and his colleagues asked not only for the right to marry into the elite: they also demanded the right to stand for the consulship, the supreme magistracy denied to plebeians. the senate refused outright to open the consulship, but contrived a detour so as not to give way on the essentials. instead of consuls, in some years “military tribunes with consular power” would be elected, an expandable college of magistrates with the command of consuls but without their prestige or their sacred insignia. and to that office plebeians could indeed aspire. it was a calculated concession — to grant the function while withholding the title — and for decades rome would alternate between consuls and consular tribunes according to the balance of strength between the two orders. the full consulship would still take almost a century to open, but the breach had already been opened.
modern history qualifies, as always, the heroic account: the details of canuleius’s speech as livy hands them down are later rhetorical reconstruction, and one should be wary of the clarity with which the sources present each plebeian victory as a pitched battle. but the central fact — the legal opening of mixed marriage around the middle of the 5th century — is held to be historical, and it fits with what we know of the “conflict of the orders”: a long cold war in which the plebs used its military weight again and again as a bargaining chip. the next time that mixed army marched as one, however, it would not be to wrench rights at home: it would be to wipe its greatest neighbour from the map.
