The three major political divisions of the Peninsula are the products of history rather than geography: the kingdom of Italy, part of the Western Empire, embraced most of the north and Tuscany; the Papal States ran, roughly, diagonally from the Adriatic to the Tyrrhenian seas; in the south was the Regno, the kingdom of Naples. Around the Italian coasts, a series of islands were barely considered by contemporaries as forming part of Italy: Sicily, which in the period became firmly associated with Naples under the same Aragonese dynasty; Sardinia and Corisica, battled over by the Aragonese and Genoa; over the islands of the Dalmatian coast Venice extended her rule, as she did over parts of Greece and some of the Greek islands until they were overrun by the Ottoman Turks. But the basic distinctions — between the north, the Papal States, and the Regno — owed their existence to centuries of warfare between the empire and the papacy.

… Within Italy itself Venice and Milan were dominant in large measure over their neighbors, and there has always been a temptation to write Italian political history in terms of these large and often aggressive units, along with Florence and Naples. But in fact such divisions of Italy do less than justice to the reality of the smaller centers of power. These are particularly prominent in the Papal STates. Rome was economically weak compared with the cities mentioned, and it’s authority as a ‘capital’ city could be weakened still further when rebellious subjects of the Papal States appealed to the doctrine which made a general council the ultimate source of authority in the Church. On the other hand, Rome had a tradition depending not only on the power of the papacy but on the saints it harboured and the privileges it could confer through jubilees, held ever more frequently as the 15th century advanced. The papacy also claimed overlordship of the Regno and the greater islands, and the growing power of Aragon in the region was hindered by the support the popes could give to a rival dynasty with claims in the region, the French house of Anjou.

This divided and subdivided land was the scene of extraordinarily tenacious struggles for power which could both strengthen and weaken the authority of the state. The story begins at the end of the 14th century and ends in the third decade of the 16th. By then the outside pressures had changed. The Hapsburg emperors were now also the rulers of a unifying Spain, which controlled much of Central and South America. The years of the French invasions of Italy coincided with the arrival of silver and gold from across the Atlantic, and the economic picture for the Peninsula, as for Europe as a whole, was to be transformed. Finally, the whispers of criticism of the old Church which had already been faintly heard in Italy culminated in the storm of Luther, and gave added significance to the Sack of Rome in 1527.

The century and a half between the outbreak of the Great Schism and the Sack of Rome (1378-1527) saw a gradual build-up of international rivalries of which Italy became increasingly the center… As a result, the tangled internal politics of Italy can appear to lack coherence beyond the struggle for territory, commercial advantage and autonomy between states, and the struggle for authority within them… This incoherence, it is often argued, was arrested by the Peace of Lodi (April 1454), followed by the creation of the Italian League. The events of 1454-55 certainly ushered in a somewhat different pattern for Italian politics and provide a suitable break in this chapter. They also represented one of the rare instances when Italian governments showed awareness of the dangers of foreign attack as well as of their own internal weakness. On the first point, it is remarkable that there was virtually no realisation on the part of the Italians that their states, relatively small in terms of area, population and resources, were increasingly exposed to challenges of a totally different order of magnitude from those once posed by the emperors Frederick I and Frederick II. There were hints of such an awareness in the mid 15th century crisis but it is hard to find the raw facts, based on comparisons of scale, explicitly referred to by Italian or indeed by northern observers. Only a few fugitive allusions go beyond the traditional platitudes that the Alps sheltered Italy from barbarism.

Today, with the advantage of hindsight, it is hard for a non-Italian not to find the sharpest of contrasts between the peninsular world and the rest of Europe where, during this period, the ‘nation-states’ were forming. It is true that Germany was as divided as Italy, but it formed the central part of an empire theoretically under the leadership of the dynasties of Luxembourg and Hapsburg and it was emotionally, and sometimes physically, given a greater sense of unity by fear of the Ottoman Turks. The Spanish kingdoms and the bulk of transalpine Europe offered, so it might seem, a pattern for political development which Italy was not to follow until the Risorgimento.

Yet it would be a mistake and an anachronism to exaggerate the Italian-non-Italian contrast as it existed at the end of the 14th century. If at the time Italy was entering a period of even more intensified division, the future ‘great powers’ were almost as enfeebled, if not so formally divided. France, the future center of autocratic rule, did not arrive at that position until much later; for much of this period the country was divided by a bitter civil war, traditionally referred to as the struggle between Burgundians and Armagnacs, as well as experiencing the threat and reality of foreign invasion. England witnessed the upheavals of Richard II’s reign — an introduction, as it proved, to the so-called ‘Wars of the Roses’ of the mid-15th century. Arogonese royal power was checked by assertive consultative assemblies, the Cortes, as well as being dispersed in the political ambitions of its expansion in the western Mediterranean. The Castilian crown was beset by an ambitious nobility, and remained preoccupied with the completion of the Reconquista of Moslem Grenada. Nothing in the general European scene in the decades around 1400 could have suggested a marked contrast between weak powers in Italy and strong states on its frontiers. The Italians saw themselves as dwelling in a land of towns, and in this they differed from an England of counties and a France where provincial life survived with vigour. But disorder and disobedience were endemic in every part of Christendom.

1378 was notable not only for rioting in Florence but also for an occurrence which was to have longer-term and more widely spread repercussions. This was the year in which the Great Schism began, tearing the CHurch apart and complicating the ecclesiastical organization of Europe as a whole and of Italy in particular. The political effect on Italy was all the greater because a pope now resided, or attempted to reside, in Rome and became increasingly dependent on the Italians for obedience. Earlier, from 1308 to 1376, the papacy had been based at Avignon and had rarely resided in Rome for a century before that. Moreover, in the Avignon period all the popes had been Frenchmen, while Frenchmen predominated in the college of cardinals and the papal administration, the Curia Romana. Rome itself was threatened by the kingdom of Naples, which almost encircled it and found ready allies in the contumacious and opportunistic baronage of Umbria and Lazio. This kingdom, now in the hands of the last of the Angevins imported in the late 13th century by the papacy as allies aimed to expand in two areas: to the north of Italy and in the Balkans. This was perhaps the first non-Italian influence to make itself felt. But south of Naples, and detached from it since 1282, lay the kingdom of Sicily ruled by Aragonese princes, who were able to establish themselves in Naples from 1442 and in this way forge a link between the fortunes of Italy and Spain which was to endure for centuries.

The small political units which comprised the Papal States during the absence of the popes at Avignon had in many ways emancipated themselves from the control of the popes who in turn were reluctant to see their remaining territorial revenues in Italy eaten up by the need to bribe obedience or to employ mercenaries to enforce it. Among the states that thrived during the period of papal absence and weakness some attained greater coherence and stability, such as that of the Malatesta, based in Rimini. The hiatus of papal authority in central Italy favored the consolidation and expansion of the Visconti of Milan in Lombardy and beyond; the Papal States were as attractive to the Visconti from the north as they were for the Angevins from the south. The other larger states of Italy were generally content with more local ambitions. Florence slowly extended her influence and authority in Tuscany. Venice was anxious for the security of her immediate hinterland, while her commercial lifelines encouraged more expansionist policies in Istria, Dalmatia, the Balkans, and the Levant. Genoa struggled to extend her trade in both the eastern and the western Mediterranean, but territorial expansion nearer home was compromised by internal political weakness and the presence of an increasingly powerful neighbor, the counts of Savoy.

Even this tangeled picture does not do full justice to the complicated political situation in 14th century Italy. It omits the ambitions and fortunes of the Carrara family at Padua, the Este at Ferrara, the Gonzaga at Mantua and many other smaller lordships and towns which were often anxiously dependent on the patronage and alliance of powerful neighbors. In general, lordships — signorie — had become the predominant form of government in northern and central Italy, but the ruling families, whether of recent or ancient origin, tended to avoid radical change.
But in Italy as  whole divisions were exacerbated by the Schism. Divisions could also lead to non-Italian intervention in the affairs of the Peninsula. Such intervention was hardly surprising given the bitterness that could characterize the rivalry between Italian states.