In spite of the endemic warfare which characterized Italy from the 14th century to the Peace of Lodi in 1454, and the occasional wars thereafter (e.g. those of Volterera, 1472, of the Papacy and Naples against Florence, 1478-80, and of Ferrara, 1482-84), by general consensus the Wars of Italy are held to be those that began in 1494 with Charles VIII'S invasion of the peninsula, came virtually to an end with the Habsburg-Valois treaties of Barcelona and Cambrai in 1529, and were finally concluded with the European settlement of Cateau-Cambresis in 1559.
The wars from 1494 do, in fact, fall into a different category from those that preceded them. Campaign followed campaign on a scale and with an unremittingness sharply different from those which had interrupted the post-Lodi peacefulness. Though foreign intervention in Italian affairs was certainly no novelty, the peninsula had never before been seen so consistently by dynastic contenders as both prize and arena. No previous series of combats had produced such lasting effects: the subjection of Milan and Naples to direct Spanish rule and the ossification of politics until the arrival in 1796 of a new Charles VIII in the person of Napoleon Bonaparte. The wars were also recognized as different in kind from their predecessors by those who lived through them: 'before. 1494' and 'after 1494' became phrases charged with nostalgic regret for, and appalled recognition of, the demoted status of the previously quarrelsome but in the main independent comity of peninsular powers. And because the wars forced the rest of western Europe into new alliances and a novel diplomatic closeness, they were from the 18th century until comparatively recently seen as marking the turn from medieval to recognizably modern political times.
The wars, then, were caused by foreign intervention. In these terms they can be chronicled with some brevity. After crossing the Alps in 1494 Charles VIII conquered the kingdom of Naples and retired in 1495, leaving the kingdom garrisoned. The garrisons were attacked later in the same year by Spanish troops under Gonzalo de Cordoba, sent by King Ferdinand II of Aragon (who was also King of Sicily). With this assistance Naples was restored to its native Aragonese dynasty. In 1499 the new King of France, Louis XII, assumed the title Duke of Milan (inherited through his grandfather's marriage to a Visconti) and occupied the duchy, taking over Genoa later in the same year. In 1501 a joint Franco-Spanish expedition reconquered the kingdom of Naples. The allies then fell out and fought one another. By January 1504 Spain controlled the whole southern kingdom, leaving France in control of Milan and Genoa in the north. A third foreign power, the German Habsburg Emperor Maximilian I entered the arena in 1508 with an abortive invasion of the Veronese-Vicentino. He countered the rebuff by joining the allies of the anti-Venetian League of Cambrai: France and Aragon assisted by Pope Julius II and the rulers of Mantua and Ferrara. In 1509 their victory at Agnadello led to the occupation of the whole of the Venetian terraferma apart from Treviso.
The eastward extension of French power gained by this victory (won by a mainly French army) drove Julius and Ferdinand to turn against Louis and in 1512 the French - now also under pressure from a fourth foreign power interesting itself in Italian territory, the Swiss - were forced to evacuate their possessions in Lombardy. Louis's last invasion of the Milanese was turned back in 1513 at the battle of Novara and the duchy was restored to its native dynasty, the Sforza, in the person of Massimiliano; he ruled, however, under the supervision of Milan's real masters, the Swiss. In 1515, with a new French king, Francis I, came a new invasion and a successful one: the Swiss were defeated at Marignano and Massimiliano ceded his title to Francis. To confirm his monopoly of foreign intervention in the north Francis persuaded Maximilian I to withdraw his garrisons from Venetian territory, thus aiding the Republic to complete the recovery of its terraferma.
With the spirit of the Swiss broken, the death of Ferdinand in 1516 and of Maximilian I in 1519 appeared to betoken an era of stability for a peninsula that on the whole took Spanish rule in the south and French in the north-west for granted. However, on Maximilian's death his grandson Charles, who had already become King of Spain in succession to Ferdinand, was elected Emperor as Charles V; Genoa and Milan formed an obvious land bridge between his Spanish and German lands, and a base for communications and troop movements thence to his other hereditary possessions in Burgundy and the Netherlands. Equally, it was clear to Francis I that his Italian territories were no longer a luxury, but strategically essential were his land frontier not to be encircled all the way from Provence to Artois. Spanish, German and French interests were now all centred on one area of Italy and a new phase of the wars began.
Between 1521 and 1523 the French were expelled from Genoa and the whole of the Milanese. A French counter-attack late in 1523, followed by a fresh invasion in 1524 under Francis himself, led, after many changes of fortune, to the battle of Pavia in 1525; not only were the French defeated, but Francis himself was sent as a prisoner to Spain, and released in 1526 only on condition that he surrender all claims to Italian territory. But by now political words were the most fragile of bonds. Francis allied himself by the Treaty of Cognac to Pope Clement VII, previously a supporter of Charles but, like Julius II in 1510, dismayed by the consequences of what he had encouraged, and the Milanese once more became a theatre of war. In 1527, moreover, the contagion spread, partly by mischance - as when the main Imperial army, feebly led and underpaid, put loot above strategy and proceeded to the Sack of Rome, and partly by design - as when, in a reversion to the policy of Charles VIII, a French army marched to Naples, having forced the Imperial garrison out of Genoa on the way and secured the city's navy, under Andrea Doria, as an ally. In July 1528 it was Doria who broke what had become a Franco-Imperial stalemate by going over to the side of the Emperor and calling off the fleet from its blockade of Naples, thus forcing the French to withdraw from the siege of a city now open to Spanish reinforcements.
By 1529, defeated in Naples and winded in Milan, Francis at last allowed his ministers to throw in the sponge. The Treaty of Barcelona, supplemented by that of Cambrai, confirmed the Spanish title to Naples and the cessation of French pretensions to Milan, which was restored (though the Imperial leading strings were clearly visible) to the Sforza claimant, now Francesco II. Thereafter, though Charles took over the direct government of Milan through his son Philip on Francesco's death in 1535, and Francis I in revenge occupied Savoy and most of Piedmont in the following year, direct foreign intervention in Italy was limited to the localized War of Siena. In 1552 the Sienese expelled the garrison Charles maintained there as watchdog over his communications between Naples and Milan, and called on French support. As an ally of Charles, but really on his own account, Cosimo I, Duke of Florence, took the city after a campaign that lasted from 1554 to 1555. But in the Treaty of Cateau-CambrÚsis of 1559, by which France yet again, and now finally, renounced Italian interests, Cosimo was forced to grant Charles the right to maintain garrisons in Siena's strategic dependencies, Orbetello, Talamone and Porto Ercole.
The Wars of Italy, though caused by foreign interventions, involved and were shaped by the invitations, self-interested groupings and mutual treacheries of the Italian powers themselves. At the beginning, Charles VIII was encouraged by the Duke of Milan, Lodovico Sforza, jealous of the apparently expanding diplomatic influence of Naples, as well as by exiles and malcontents (including the future Julius II) who thought that a violent tap on the peninsular kaleidoscope might provide space for their own ambitions. And the 1529 Treaty of Cambrai did not put an end to the local repercussions of the Franco Imperial conflict. France's ally Venice only withdrew from the kingdom of Naples after the subsequent (December 1529) settlement negotiated at Bologna. It was not until August 1530 that the Last Florentine Republic gave in to the siege by the Imperialist army supporting the exiled Medici. The changes of heart and loyalty on the part of Julius II in 1510 and Clement VII in 1526 are but illustrations of the weaving and reweaving of alliances that determined the individual fortunes of the Italian states within the interventionist framework: no prÚcis can combine them.
A final point may, however, be made. Whatever the economic and psychological strain produced in individual states by their involvement, and the consequential changes in their constitutions or masters, no overall correlation between the Wars and the culture of Italy can be made. The battles were fought in the countryside and peasants were the chief sufferers from the campaigns. Sieges of great cities were few, and, save in the cases of Naples in 1527-28 and Florence in 1529-30, short. No planned military occasion had so grievious effect as did the Sack of Rome, which aborted the city's cultural life for a decade.