If you wonder about the relationship between the main city states of Renaissance Italy, think about the daily soaps where everyone is in bed with everyone else between adulterous or murderous plots. War was the norm for the Italian states during these centuries, peace the exception. The major powers fought one another mainly by pitching one hired mercenary army against another. Successful mercenary captains were much in demand, and these men moved from one employer to another without regard to loyalty. The Italian states had little trust in their own generals, and even less in eachother.
Why such bloody conflict between neighbors? It helps to examine a map of Italy from the 15th century to get an idea of how the land was carved up. Italy as a single nation, of course, didn’t exist. The peninsula held numerous territories controlled by town councils, local lords, papal governors or wealthy families. In general, the peninsula was divided into: the Kingdom of Naples, the Papal States, the Duchy of Milan and the republics of Siena, Florence and Venice. Within and around these main territories clustered smaller powers such as the Duchies of Modena, Ferrara and Urbino. In most cases, citizens had loyalty only to their home towns and often viewed anyone from another city as foreign.
The borders between city states shifted continously. Wars often broke out because of suspicions that a rival power plotted to expand at the expense of a neighbor. The age-old conflict between Florence and its smaller Tuscan neighbor Siena is a prime example. The cities were at war over the control of abundant towns, marble quarries, vineyards, prime farmlands, and ports on the Mediterranean coast. This last was especially important to Florence, which for centuries was a land-locked country. The central conflict between Florence and Siena spawned a balance of power struggle in all of north-central Italy. Siena sided with Milan to make Florence fear a Milanese foothold for invasion on its southern border. In retaliation, Florence allied with Venice, traditional enemy of Milan. When Venice became too aggressive on the Italian mainland, Florence allied with Milan, and the balance of power shuffled again like a complex card deal.
The major political players in Renaissance Italy:
The Republic of Venice
“La Serenissima” or the Most Serene Republic, at its height controlled land on the borders of Milan including Bergamo, Brescia and Verona, down through Padua to the east, and the north and eastern coasts along the Adriatic Sea. Control of the coasts of Croatia and Bosnia on the eastern Adriatic were crucial for Venice, whose navy made sure Venetian trade ships from the East were safe.
The Duchy of Milan
During Francesco Sforza´s time, Milan reached nearly to the Rhine River in the north, bordered Savoy and Genoa in the west, Venice in the east, and touched Mantua, Modena and Malaspina to the south. Successful wars or diplomacy had at times given Milan control of Bergamo, Brescia, Feltre, Vicenza and Verona (from Venice); Emila and Perugia (from the Papal States); Pisa and surrounding territories and northwestern Siena.
The Republic of Florence
In the heart of Tuscany, the Florentine territories bordered Lucca, Modena, the Papal States and Siena. Main Florentine cities included Pistoia, Prato, Arezzo, Volterra and later Pisa. Florence remained small in territory, but its wealth made up for it.
The Papal States
These were loosely controlled by the Papacy, if at all. The territory included the Romagna and the Marches in eastern Italy, Umbria in the center, and the western coast from roughly Civitavecchia through Ostia and down through Terracina. The Romagna and the Marches were mainly controlled by local lords with only nominal alliance with the Papacy.
The Kingdom of Naples and Sicily
It was the lower “boot” portion of the peninsula. The kingdom stretched from Aquila in central Italy south along the coasts of the Adriatic and Tyrrenian Seas, through Apulia and Calabria. It was controlled by the royal House of Aragon until the Spanish throne took over between 1479 (in Sicily and Sardinia) through 1504 (the mainland).