The mainspring of Roman success was the policy of agrarian expansion, and the farmers were the first to profit by it. This fact rendered impossible the development of a municipal democracy after the Greek model (such as Appius Claudius had attempted to set up in 308) based upon capital, trade, and handicraft, and the masses of the urban population, with an all-powerful demagogue at its head. From that time forward the urban population, restricted as it was to four districts, was practically overridden, as far as political rights were concerned, in the _comitia tributa_ (with which ordinary legislation rested) by the thirty-one districts of the agricultural class. But as the state grew into a great power and its chief town into a metropolis, the urban elements could not fail to acquire increasing influence, especially the wealthy capitalists (consisting largely of freedmen and the descendants of freedmen) who managed all matters of public finance. In the _comitia centuriata_ which were organised on the basis of a property qualification, and whose functions included the election of magistrates and the settlement of peace and war, these circles exercised very great influence, and the wealthiest found a compact organisation in the eighteen centuries of knights. The interests of the agricultural class did not extend beyond Italy; the late wars had provided plenty of land for distribution, and if more were wanted it could be found in the territory of the Celts on the Po, the southern portion of which had been conquered as early as 282 but not yet divided. The interests of the urban elements, the capitalists, on the contrary, extended beyond the sea. To them the most pressing business of the moment was to vindicate the preponderance of the state to the outside world, to adjust their relations abroad as best suited their own interests, and to deliver Italy from foreign competition, and, above all, from Carthage; and not a few of the great ruling families were allured, like the Claudii, by the tempting prospect. Carthage and Rome had come dangerously near together during the last few decades. As long before as the year 306 the two had concluded a compact by which Rome was not to intervene in Sicily nor Carthage in Italy. The rival states had indeed united against Pyrrhus, but without ever laying aside their mutual distrust; each feared that the other might effect a lodgment within its sphere of influence. And now, in the year 264, the Oscan community of the Mamertines in Messana (whilom mercenaries of Agathocles, who had exterminated the Greek inhabitants of the city) appealed to both Carthage and Rome for aid against Hiero, the ruler of Syracuse.