The political jealousy, embittered by personal emulation, which existed between the Emperor and the King of France, broke out into war in 1521. France, Navarre, and the Low Countries were at times the seat of the long contest which ensued; but chiefly Italy. The duchy of Milan had been conquered by Francis in 1515. It was again wrested from the French by the emperor in 1522. In 1523, a strong confederacy was formed against France, by the Pope, the Emperor, the King of England, the Archduke Ferdinand, to whom his brother Charles had ceded the German dominions of the House of Austria, the states of Milan, Venice, and Genoa; all united against a single power. And in addition, the celebrated Constable of Bourbon became a traitor to France to gratify his revenge; brought his brilliant military talents to the emperor's service, and was invested with the command of the Imperial troops in Italy. To this formidable enemy Francis opposed his weak and presumptuous favorite, the Admiral Bonnivet, who was driven out of Italy in 1524, the year in which the gallant Bayard lost his life in striving to redeem his commander's errors.
The confidence of Francis seemed to increase with his dangers, and his faults with his confidence. He again entered the Milanese in 1525, and retook the capital. But Bonnivet was his only counsellor; and under such guidance the siege of Pavia was prosecuted with inconceivable rashness, and the battle of Pavia fought without a chance of gaining it. Francis was taken prisoner, and wrote thus to his mother, the Duchess of Angoulême: "Everything is lost, except our honor." This Spartan spirit has been much admired; but whether justly, may be a question. From a Bayard, nothing could have been better; but the honor of a king is not confined to fighting a battle; and this specimen, like the conduct of Francis in general, proves him to have been the mirror of knighthood, rather than of royalty.
Charles, notwithstanding his victory at Pavia, did not invade France, but, as the price of freedom, he prescribed the harshest conditions to the captive king. At first they were rejected, but his haughty spirit and conscience were at length both reconciled to the casuistry that the fulfilment of forced promises may be eluded. Francis, therefore, consented to the treaty of Madrid, made in 1526, by which it was stipulated that he should give up his claims in Italy and the Low Countries; surrender the Duchy of Burgundy to Spain; and return into captivity if these conditions were not fulfilled in six weeks. When once at large, instead of executing the treaty, he formed a league with the Pope, the King of England, and the Venetians, to maintain the liberty of Italy. The Pope absolved him from his oaths, and he refused to return into Spain. The passions of the rival monarchs were now much excited, and challenges and the lie were exchanged between them. No duel was fought, nor probably intended; but the notoriety of the challenge went far to establish a false point of punctilio, we will not call it honor, among gentlemen, and single combats became more frequent than in the ages of barbarism.