The wars began when, in 1494, Charles VIII of France invaded Italy and seized (1495) Naples without effort, only to be forced to retreat by a coalition of Spain, the Holy Roman emperor, the pope, Venice, and Milan. His successor, Louis XII, occupied (1499) Milan and Genoa. Louis gained his next objective, Naples, by agreeing to its conquest and partition with Ferdinand V of Spain and by securing the consent of Pope Alexander VI. Disagreement over division of the spoils between the Spanish and the French, however, flared into open warfare in 1502. Louis XII was forced to consent to the Treaties of Blois (1504-5), keeping Milan and Genoa but pledging Naples to Spain.
Trouble began again when Pope Julius II formed (1508) an alliance against Venice with France, Spain, and Holy Roman Emperor Maximilian I (see Cambrai, League of). But shortly after the French victory over the Venetians at Agnadello (1509), Julius made peace with Venice and began to form the Holy League (1510) in order to expel the French "barbarians" from Italy. The French held their own until the Swiss stormed Milan (1512)—which they nominally restored to the Sforzas—routed the French at Novara (1513), and controlled Lombardy until they were defeated in turn by Louis's successor, Francis I, at Marignano (1515). By the peace of Noyon (1516), Naples remained in Spanish hands and Milan was returned to France.
The rivalry between Francis I and Charles V, king of Spain and (after 1519) Holy Roman emperor, reopened warfare in 1521, and the French were badly defeated in the Battle of Pavia (1525), the most important in the long wars. Francis was forced to sign the Treaty of Madrid (1526), by which he renounced his Italian claims and ceded Burgundy. This he repudiated, as soon as he was liberated, by forming the League of Cognac with Pope Clement VII, Henry VIII of England, Venice, and Florence.
To punish the pope, Charles V sent Charles de Bourbon against Rome, which was sacked for a full week (May, 1527). The French, after an early success at Genoa, were eventually forced to abandon their siege of Naples and retreat. The war ended (1529) with the Treaty of Cambrai (see Cambrai, Treaty of) and the renunciation of Francis's claims in Italy. France's two subsequent wars (1542-44 and 1556-57) ended in failure. Francis died in 1547, having renounced Naples (for the third time) in the Treaty of Crépy. Complete Spanish supremacy in Italy was obtained by the Treaty of Cateau-Cambrésis (1559), which gave the Two Sicilies and Milan to Philip II.
The wars, though ruinous to Italy, had helped to spread the Italian Renaissance in Western Europe. From the military viewpoint, they signified the passing of chivalry, which found its last great representative in the seigneur de Bayard. The use of Swiss and German mercenaries was characteristic of the wars, and artillery passed its first major test.
See F. L. Taylor, Art of War in Italy, 1494 to 1529 (1921).
Ludovico Sforza of Milan, seeking an ally against the Republic of Venice, encouraged Charles VIII of France to invade Italy, using the Angevin claim to the throne of Naples as a pretext. When Ferdinand I of Naples died in 1494, Charles invaded the peninsula with 25,000 men (including 8,000 Swiss mercenaries), possibly hoping to use Naples as a base for a crusade against the Turks. For several months, French forces moved through Italy virtually unopposed, since the condottieri armies of the Italian city-states were unable to resist them. Their sack of Naples finally provoked a reaction, however, and the League of Venice was formed against them, effectively cutting off Charles's army from France. Despite a tactical victory of French armies against the League at the battle of Fornovo, the formation of the League to his rear forced Charles to withdraw to France, Fornovo itself being merely a successful fighting withdrawal. After initial reverses, most notably the disastrous Battle of Seminara, Ferdinand II of Naples, with the able assistance of the Spanish general Gonzalo Fernández de Córdoba, reduced the French garrison in the Kingdom of Naples. Ludovico, having betrayed the French at Fornovo, retained his throne until 1499, when Charles's successor, Louis XII of France, invaded Lombardy and seized Milan.
In 1500, Louis, having reached an agreement with Ferdinand I of Spain to divide Naples, marched south from Milan. By 1502, combined French and Spanish forces had seized control of the Kingdom; disagreements about the terms of the partition led to a war between Louis and Ferdinand. By 1503, Louis, having been defeated at the Battle of Cerignola and Battle of Garigliano, was forced to withdraw from Naples, which was left under the control of General de Córdoba, the Spanish viceroy.
Meanwhile, Pope Julius II was more concerned with curbing the territorial expansion of the Republic of Venice, and in 1508 formed the League of Cambrai, in which France, the Papacy, Spain and the Holy Roman Empire agreed to restrain the Venetians. Although the League destroyed much of the Venetian army at the Battle of Agnadello in 1509, it failed to capture Padua, and in 1510, Julius, now regarding France as a greater threat, left the League and allied himself with Venice. Following a year of fighting over the Romagna, during which the Veneto-Papal alliance was repeatedly defeated, the Pope proclaimed a Holy League against the French; this rapidly grew to include England, Spain, and the Holy Roman Empire.
French forces under Gaston de Foix inflicted an overwhelming defeat on a Spanish army at the Battle of Ravenna in 1512, but Foix was killed during the battle, and the French were forced to withdraw from Italy by an invasion of Milan by the Swiss, who reinstated Maximilian Sforza to the ducal throne. The Holy League, left victorious, fell apart over the subject of dividing the spoils, and in 1513 Venice allied with France, agreeing to partition Lombardy between them.
Louis mounted another invasion of Milan, but was defeated at the battle of Novara, which was quickly followed by a series of Holy League victories at La Motta, Guinegate, and Flodden Field, in which the French, Venetian, and Scottish forces were decisively defeated. However, the death of Julius left the League without effective leadership, and when Louis' successor, Francis I, defeated the Swiss at Marignano in 1515, the League collapsed, and by the treaties of Noyon and Brussels, surrendered to France and Venice the entirety of northern Italy.
The elevation of Charles of Spain to Holy Roman Emperor, a position that Francis had desired, led to a collapse of relations between France and the Habsburgs. In 1519, a Spanish invasion of Navarre, nominally a French fief, provided Francis with a pretext for starting a general war; French forces flooded into Italy and began a campaign to drive Charles from Naples. The French were outmatched, however, by the Spanish arquebusier tactics, and suffered a series of crippling defeats at Bicocca and Sesia against Spanish troops under Fernando de Avalos. With Milan itself threatened, Francis personally led a French army into Lombardy in 1525, only to be defeated and captured at the battle of Pavia; imprisoned in Madrid, Francis was forced to agree to extensive concessions over his Italian territories.
In 1526, Pope Clement VII, alarmed at the growing power of the Empire, formed the League of Cognac against Charles V, allying himself, the Republic of Venice, Florence, and a number of smaller Italian states with France. Venice, however, refused to contribute troops; with the withdrawal of French forces from Lombardy, Charles V proceeded to subdue Florence, and, in 1527, sack Rome itself. Clement was imprisoned by Imperial troops, and offered no further resistance to Charles V. With the conclusion of the Treaty of Cambrai in 1529, which formally removed Francis from the war, the League collapsed; Venice made peace with Charles V, while Florence was placed again under the Medici.
The third war between Charles and Francis began with the death of Francesco Maria Sforza, the duke of Milan. When Charles's son Phillip inherited the duchy, Francis invaded Italy, capturing Turin, but failed to take Milan. In response, Charles invaded Provence, advancing to Aix-en-Provence, but withdrew to Spain rather than attacking the heavily fortified Avignon. The Truce of Nice ended the war, leaving Turin in French hands but effecting no significant changes to the map of Italy.
Francis, allying himself with Suleiman I of the Ottoman Empire, launched a final invasion of Italy. A Franco-Ottoman fleet captured the city of Nice in August 1543, and laid siege to the citadel. The defenders were relieved within a month. The French, under François, Count d'Enghien, defeated an Imperial army at the Battle of Ceresole in 1544, but the French failed to penetrate further into Lombardy. Charles and Henry VIII of England then proceeded to invade northern France, seizing Boulogne and Soissons. A lack of cooperation between the Spanish and English armies, coupled with increasingly aggressive Ottoman attacks, led Charles to abandon these conquests, restoring the status quo once again.
In 1551, Henry II of France, who had succeeded Francis to the throne, declared war against Charles with the intent of recapturing Italy and ensuring French, rather than Habsburg, domination of European affairs. An early offensive against Lorraine was successful, but the attempted French invasion of Tuscany in 1553 was defeated at the Battle of Marciano. Charles' abdication in 1556 split the Habsburg empire between Phillip II of Spain and Ferdinand I, and shifted the focus of the war to Flanders, where Phillip, in conjunction with Emmanuel Philibert of Savoy, defeated the French at St. Quentin. England's entry into the war later that year led to the French capture of Calais, and French armies plundered Spanish possessions in the Low Countries; but Henry was nonetheless forced to accept the Peace of Cateau-Cambrésis, in which he renounced any further claims to Italy.
The Italian Wars had a number of consequences for the work and workplace of Leonardo da Vinci, for example scuppering his plans for a "Gran Cavallo" horse statue in 1495 when the seventy tons of bronze were instead cast into weapons to save Milan.
The armies of the Italian Wars were commanded by a wide variety of different leaders, from mercenaries and condottiere to nobles and kings.