Charles V, Emperor of Germany, was at this time the greatest and most powerful sovereign in Europe. He had inherited the kingdoms of Spain, the Netherlands, Naples and Sicily, as well as his possessions in Germany. Born six years later than Solyman, he was elected Emperor of Germany a year before the accession of Solyman as Sultan. He abdicated his throne and retired to a monastery ten years before the death of Solyman. For thirty-six years, therefore, their reigns were synchronous. It would be hard to say which of the two sovereigns was the more valiant in arms, or the more astute statesman. Judged by the extent of conquests, Solyman far surpassed his rival. Charles did little more than maintain the integrity of his immense inherited possessions in Europe. But he acquired by conquest Tunis in Africa, and Mexico and Peru in America. When Solyman, instigated by Francis I of France, was invading Austria, Charles was deeply engaged in war against France in Italy, and could not send an army to meet the Ottomans in the field. Vienna was left to stand the brunt of invasion without a protecting army. Its garrison consisted of only sixteen thousand soldiers under Count de Salms. Its fortifications were only a continuous wall 5 feet in thickness and without bastions. Its guns were only seventy-two in number. Such weak defences seemed to offer little hope against the overwhelming numbers of the Ottomans. The tents of the Sultan and his army whitened the whole plain round the city. Irregular cavalry, called Scorchers, depending on loot for their food and pay, ravaged the country for miles round the city with incredible cruelty and rapacity. A Turkish flotilla of four hundred small vessels found its way up the Danube, after destroying all bridges, and lent assistance to the siege. It was all in vain. The Austrian and Spanish troops under the Count de Salms defended the weak lines with the utmost courage and tenacity. The Viennese citizens constructed lines of earthworks within the walls, against which the lighter guns of the Turks had little effect. The powerful siege guns of the Ottomans had been left behind _en route_, owing to heavy rains and the badness of roads. Numerous assaults were made by the Turks. The soldiers were at last dispirited by failure. In vain their officers drove them on by sticks and sabres. The men said they preferred death from their officers to death from the long arquebuses of the Spaniards. Twenty ducats a head were given or promised to them. It was to no purpose. Solyman, after three weeks of fruitless assaults, found himself compelled to raise the siege and to retreat with his great army. His irregulars had so ravaged the country that he had the utmost difficulty in feeding his men.