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 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. This deliberate infraction of an oath savoured neither of the mirror of knighthood, nor royalty. Nor did the Emperor appear to advantage in this transaction: his want of generosity was conspicuous in his extravagant demands, and his failure in the higher tone of princely feeling was not compensated to himself by the success of his politics. In 1527, Bourbon laid siege to Rome, and was slain in the assault; but the Imperialists took and plundered the city, and are said in derision to have proclaimed Martin Luther Pope. The Emperor’s conduct on this occasion was not less farcical, than his hypocrisy was disgusting. On receiving news of the captivity of the head of the church, instead of setting him at liberty, he commanded processions for his deliverance, and ultimately exacted from him a heavy ransom. Meanwhile the treaty of Madrid was not fulfilled; and this was the cause of another war between Spain, and France supported by England. 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 honour, among gentlemen, and single combats became more frequent than in the ages of barbarism. In 1529, the course of these calamities was suspended by the treaty of Cambray, negotiated in person by two women. The Duchess of Angoulême, and Margaret of Austria, governess of the Low Countries, met in that city, and settled the terms of pacification between the rival monarchs.