The Second Hapsburg-Valois War or War of the League of Cognac (1526-30) was an unsuccessful attempt to reduce the power of Charles V in Italy after his crushing victory at Pavia in 1525, and is perhaps best known for a disastrous sack of Rome in 1527 (Italian Wars, 1494-1559).
At the start of the First Hapsburg-Valois War (1526-30) there had been something of a balance of power in Italy. Francis I of France held Milan while the Emperor Charles V ruled in Sicily and Naples. Venice dominated the north-east, the Papal States in the centre of Italy, and a handful of smaller states, most notably Florence and Genoa, filled the gaps. That balance of power was shattered by the Battle of Pavia (24 February 1525). Francis I was captured and taken to Madrid, where he was forced to sign the Treaty of Madrid (14 January 1526) in which he surrendered his claims to Milan, Naples, Genoa, Flanders, Artois, Tournai, and the duchy of Burgundy.
The Imperial victory worried powers all across Italy. Pope Clement VII, who had supported Charles against the French, began to try and create an anti-Imperial league. He was able to win over Florence (where his own Medici family was powerful) and Venice (a long-term opponent of Imperial power in Italy). More surprising was the attitude of Francesco Sforza, duke of Milan, who had been placed in power by Imperial arms. He began to turn against Charles in 1525. His chancellor, Gurolame Morone, attempted to win over the Imperial commander Ferdinando Francesco d'Avalos, Marquis of Pescara. Pescara appeared to go along with the plot before in October arresting Morone and beginning a siege of the Sforza castle at Milan.
Francis I was released at the French border on 17 March 1526. He very quickly made it clear that he had no intention of honouring the Treaty of Madrid, and instead on 22 May he joined the League of Cognac, along with the Pope, Milan, Venice and Florence. Henry VIII of England supported the league but didn’t join it.
Although Francis had joined the League, he didn’t make much of a contribution to the early stages of the fighting. The first fighting came in Lombardy, and was between League forces from Venice, the Papal States and Milan and Imperial forces under Antonio de Leyva, Alfonso del Guasto and later Charles, duke of Bourbon. The fighting began with de Leyva and del Guasto besieging Sforza in the castle of Milan. A League relief army moved slowly towards Milan. Bourbon arrived with Imperial reinforcements on 5 July. The League relief army launched an attack on the siege lines, but failed and at the end of July the citadel surrendered to the Imperial forces.
The League army, under Francesco Maria, duke of Urbino, moved away to besiege Cremona, which fell on 23 September. He then moved back to blockade Milan, but the two month long siege had given Charles time to rush reinforcements from Spain and Germany into Italy. Urbino soon had to lift the siege of Milan, and was unable to prevent the German reinforcements joining Bourbon's army.
At the start of 1527 Pope Clement faced attack from the north and the south. In the north Bourbon was able to raise just enough money to keep his army together, while in the south the Spanish under Charles de Lannoy were able to counter any Papal moves. Eventually, in April, after the failure of armistice talks, Bourbon's army began to move south.
By the time it reached Rome on 5 May the army was almost out of control, lacking money and many supplies. On 6 May the Imperial army attacked Rome. Bourbon was killed early in the attack, but the city was easily captured. Pope Clement was forced to take refuge in the Castel St. Angelo while the Imperial army sacked the city. The League Army was close by, and might well have succeeded in an attack on the disordered Imperial force, but the Duke of Urbino once again chose not to act.
The Pope was forced to come to terms, paying 400,000 ducats and agreeing to surrender Ostia, Civita Vecchia, Piacenza and Modena (only the first two actually surrendered to the Imperialists).
Elsewhere Francis had at least achieved a diplomatic success, agreeing the Treaty of Westminster with Henry VIII (30 April 1527, officially confirmed 29 May). Henry was at least partly motivated by his design to divorce Catherine of Aragon, the aunt of Charles V - he would never get papal approval for the divorce unless the Pope could be rescued from Imperial power. Henry agreed to provide funds to support Francis in another campaign in Italy, with the ambitious aims of rescuing the Pope and convincing Charles to surrender his claim to Burgundy.
In July a French army under Odet, count of Lautrec, invaded Lombardy. He was aided by Andrea Doria, the great naval leader, who expelled the Imperialists from his home city of Genoa. At the same time Lautrec was able to capture Alessandria and Pavia and the western parts of Lombardy. He then turned south in an attempt to help Pope Clement, but on 26 November, before Lautrec could reach Rome, the Pope made peace with the Emperor.
By the end of 1527 both sides were beginning to desire peace. Francis offered terms, which Charles rejected. In January 1528 France and England officially declared war. At this point Francis and Charles came quite close to actually fighting a dual to decide the issue, but the proposal never came to anything.
While this was going on Lautrec continued to move south. He was able to get through the Papal States, and by the spring of 1528 the French, with the help of Andrea Doria, were besieging Naples. On 28 April 1528 Filippino Doria defeated a force of Spanish galleys outside Naples (naval battle of Naples), and the defenders appeared to be in trouble. A second French army was being raised in the north to attack Milan.
Once again Francis managed to undermine his own position, this time by alienating Andrea Doria, at least in part with his efforts to improve the rival port of Savona. Doria complained about this plan and Francis attempted to arrest him. Charles V was able to win over Doria, and at the start of June he withdrew the fleet from Naples. Supplies were rushed into the city, and French efforts to get food to their army were now hindered by the Genoese fleet. On 16 August Lautrec died, and on 28 August the siege was lifted. A short time later the survivors of the army were forced to surrender. In September Doria captured Genoa, where he installed a new form of Republican rule that lasted until the French Revolutionary Wars!
The remaining French army, under St. Pol, had some short-lived successes in the north. They captured Pavia, but failed in an attempt to retake Genoa. In late October the last French troops in Genoa, who had been holding out in the Castelletto, surrendered.
By 1529 the French needed peace. They had lost one army at Naples, along with most of their earlier conquests in Lombardy. St Pol was still active in the north, and in the spring he attempted to blockade Milan by creating a series of strong points around the city. He then abandoned this plan and instead made an attempt to capture Genoa with a surprise attack. Instead St. Pol was surprised and defeated at the battle of Landriano (20 or 21 June 1529).
While this last campaign was going on peace negotiations had already begin, between Francis I's mother Louise of Savoy and Charles V's aunt Margaret of Austria. The two met at Cambrai in July, and on 8 August the war was ended by the Peace of Cambrai (also known as the Ladies' Peace). Once again Francis officially abandoned all of his claims to Italian territory, including Milan and Naples, and to Flanders and Artois. He was to marry Eleanor of Austria, sister of Charles V (the marriage took place on 7 July 1530).
In return Charles agreed to accept a ransom of two million crowns for Francis's two eldest sons and to at least temporarily abandon his claim to Burgundy. He also acknowledged Francis's possession of the Duchy of Bourbon.
In Italy Milan was retained by Francesco Sforza, but Charles was allowed to keep a garrison in the citadel. In addition Milan was to revert to Charles after the death of Francesco.
The Pope also made a formal peace with Charles in the Treaty of Barcelona. Charles agreed to help restore the Medici in Florence and in return the Pope agreed to crown Charles as Holy Roman Emperor. The conquest of Florence took longer than expected and required a siege that lasted from October 1529 until August 1530. It ended after the Florentine commander broke out of the city only to be killed in battle at Gavinana (2 August 1530). Ten days later the city surrendered and Alesandro de Medici was officially placed in control of the government. While the siege was still going on Charles was crowned at Bologna, the last time a Holy Roman Emperor was crowned by the Pope, and then returned to Germany.
At the end of the Second Hapsburg-Valois War Charles V was the dominant power in Italy. He ruled in Naples and Sicily, was allied with the Pope, and could hope to inherit Milan. The Italian peace would last until 1536, one of the longest gaps during the entire period of the Italian Wars, and would only end after the death of Francesco Sforza in 1535. Once again this would tempt Francis to try and regain his former possessions in Italy, triggering the Third Hapsburg-Valois War (1536-38).