Meanwhile, in the course of a long process extending through the 13th and 14th centuries, within the towns of the Papal States and most towns of northern and central Italy, there arose from the old communes a new form of government, that of the signoria. The communes of the 13th century had become increasingly dominated by the conflicts of the nobility who controlled their governments. These divisions, though often moved by the Guelf and Ghibelline parties, in fact largely reflected personal, economic, or quite local political rivalries—all inflamed by ideals of chivalric honour and an everyday acceptance of the traditions of vendetta. In large part as a response to these conflicts, there had arisen within the communes the movement of the popolo—i.e., of associations of non-nobles attempting to win a variety of concessions from the nobility.

Within the ranks of the popolo were, in the first place, those who had gained wealth through trade, banking, exercise of a profession, or landholding and sought membership in the ruling noble oligarchies. The second group comprised prosperous members of the artisan or shopkeeping classes who, while not normally seeking a direct position in government, sought a more satisfactory administration of the finances of the commune (particularly a more equitable distribution of taxation), a greater voice in matters that most directly concerned them (for example, the licensing of the export of food), and, in particular, the impartial administration of justice between noble and non-noble. Above all, the popolo (like many of the nobility themselves) desired a civic order that would end violent party conflicts and lessen the effects of noble vendettas.

In some towns the popolo movement succeeded in bringing about constitutional change. In those communes where the nobility did not monopolize all wealth and where the development of trade, industry, and finance had created a complex social structure, the existing oligarchies agreed to come to terms. This came about more easily when the popolo succeeded in ending party struggles so violent that they could be described as a form of civil war. Here, often against the background of some disaster, such as defeat in war, it became normal to establish a council of the popolo, under a captain of the popolo, alongside the old council of the commune under its podesta, as a consultative element in what was now termed the government of “the commune and popolo.” In Florence, where the movement enjoyed its greatest success, the popolo, organized in seven major and five lesser guilds, assumed power in 1282 not simply as the partner of the commune in government but as the dominant element within it. Moreover, in January 1293, by the Ordinances of Justice, it declared that the members of 152 powerful families were “magnates” and, as such, excluded from personal participation in government and subject to particular disadvantages in law vis-à-vis non-magnates.

Nevertheless, in all but a few towns, the popolo proved unable to solve the problem of public order, and in these circumstances “the peaceful and tranquil state” of the cities came instead to be established by signori, who were powerful party leaders. From the second half of the 13th century, having triumphed over, destroyed, or permanently exiled their opponents, these men began to give institutional form to their power and to pass it on to their sons as a hereditary right. What they offered in return to their subject citizens was the hope of eliminating anarchic civil violence by the exercise of superior force. It was in this way that, in the course of the 14th century, signoria, or permanent legal rule by single families, began. From the communes the signori obtained their titles, the authority to control the communes “according to their own will,” and the right to pass on this grant to their chosen successors. With the passage of time, these usurped legislative trappings lent the appearance of legitimacy to their rule. By the end of the 14th century the signori normally sought some legitimization of their power by obtaining authorization from the emperor or pope to act as “vicars” over the territories that their families had come to rule. As such, during the 15th century these hereditary lordships—or, in effect, principalities—seemed to constitute the natural order in large areas of northern Italy.

So, in the Veneto, Verona fell to the della Scala (or Scaligeri) family in the 1260s, as did Vicenza from 1312, while Padua was subject to the Carrara (or Carraresi) family from 1318. In Lombardy the Bonacolsi and then, from 1328, the Gonzaga family came to be sole rulers of Mantua, while the Visconti achieved the signoria of Milan from 1311. During the next 35 years the Visconti extended their dominion by gaining power over Cremona (1334), Pavia, Lodi, Bergamo (1332), Como (1335), Piacenza (1337), Tortona, and Parma (1346). In Emilia the Este (Estense) family, already established at Ferrara from 1264, extended their power to Modena (1288) and Reggio (1290). In the northern sector of the Papal States the towns of the Romagna and the Marche fell to signori between 1315 and 1342; when Cardinal Albornoz’s attempts at reconquest failed, the papacy granted most of its territories to vicars, including these signori. Thus, between about 1250 and 1350, northern and central Italy had undergone a profound transformation in constitutional forms, political life, and attitudes toward authority. The rule of a city-state by one man was no longer seen as a strange and temporary expedient but as a normal aspect of life. Under the new regimes the councils of the communes and popolo still remained, but their role was limited to minor administrative tasks or to formal approval of the political decisions of the signori. Essentially, all that remained of the old communal system was its administrative service, a core of skilled notaries who kept the machinery of government in operation. Meanwhile, in return for their absolute power, the signori restored or created harmony within the upper classes of the towns and reconciled the interests of the popolo and the nobility.

Nonetheless, the emergence of the signorie, however important, was only one element in the constitutional history of the northern and central Italian towns in the 14th century. It was a movement largely confined to the Veneto, Lombardy, Emilia, the Marche, and—subject to the suzerainty of regional princes—Piedmont. In most towns of Umbria and Lazio (Latium) the papacy was able to prevent their establishment. In Tuscany they were largely unsuccessful. Lucca fell to signori in the first half of the 14th century, notably with the rule of the remarkable Castruccio Castracani between 1316 and 1328, but the town experienced a strong revival of republican government from 1369 to 1392. Republican Florence underwent only brief interludes of signorial governance. Florence conquered several of its neighbours—Volterra, Prato, Pistoia, San Gimignano—before any signorie arose in them. In Liguria, Genoa was continually unstable because of the violent conflicts of its noble houses. Rather than submit itself to any one family, the town oscillated between communal government and a series of popolo-granted life dictatorships—of which the most memorable was that of Simone Boccanegra, future hero of an opera by the Italian composer Giuseppe Verdi. Two communes, Siena (at least in the 14th century) and Venice, rejected signorial government entirely in favour of republican institutions.

During the 14th century then, substantial parts of Italy remained outside the control of signori. Alongside the new principates there were some communal governments—including those of Venice and Florence, two of the most powerful cities in the peninsula, which both survived and developed into powerful territorial states with very strong republican traditions. These republics survived partly because it was much more difficult for signori to seize control over a patrician oligarchy of bankers and merchants than it was to dominate a society consisting of landowners, artisans, and rural workers. Societies with highly developed economies were much less amenable to princely control. In republics, an economy that would be menaced by internal disunity and a ruling class united at least in its pursuit of commercial advantage helped assure the preservation of public order and the repulsion of any individual or family seeking political domination.