Ferdinand's son and successor, the emperor Maximilian II., was a man of tolerant views; in fact at one time he was suspected of being a Lutheran, a circumstance which greatly annoyed the Habsburgs and delayed his own election as king of the Romans. However, having given to the electors assurances of his fidelity to the Roman Church, he was chosen king in November 1562, and became ruler of Germany on his father's death nearly two years later. Like other German sovereigns Maximilian pursued the phantom of religious union. His first diet, which met at Augsburg in 1566, was, however, unable, or unwilling, to take any steps in this direction, and while the Roman Catholics urged the enforcement of the decrees of the council of Trent the serious differences among the Protestants received fresh proof from the attempt made to exclude the Calvinist prince Frederick III., elector palatine of the Rhine, from the benefits of the peace of Augsburg. After this Frederick and the Calvinists looked for sympathy more and more to the Protestants in France and the Netherlands, whom they assisted with troops, while the Lutherans, whose chief prince was Augustus, elector of Saxony, adopted a more cautious policy and were anxious not to offend the emperor. There were, moreover, troubles of a personal and private nature between these two electors and their families, and these embittered their religious differences. But these divergences of opinion were not only between Roman Catholic and Lutheran or between Lutheran and Calvinist, they were, in electoral and ducal Saxony at least, between Lutheran and Lutheran. Thus the Protestant cause was weakened just when it needed strengthening, as, on the other side, the Roman Catholics, especially Albert, duke of Bavaria, were eagerly forwarding the progress of the older faith, which towards the end of this reign was restored in the important abbey of Fulda. In secular affairs Maximilian had, just after his accession, to face a renewal of the Turkish war. Although his first diet voted liberal assistance for the defence of the country, and a large and splendid army was collected, he had gained no advantage when the campaign ended. The diet of Spires, which met in 1570, was mainly occupied in discussing measures for preventing the abuses caused by the enlistment by foreigners of German mercenary troops, but nothing was done to redress this grievance, as the estates were unwilling to accept proposals which placed more power in the emperor's hands. Maximilian found time to make earnest but unavailing efforts to mediate between his cousin, Philip II. of Spain, and the revolted Netherlands, and also to interfere in the affairs of Poland, where a faction elected him as their king. He was still dealing with this matter and hoping to gain support for it from the diet of Regensburg when he died (October 1576). Rudolph II.