The Thirty Years' War, as it is termed, which was really a series of wars, naturally falls into five distinct periods, each representing in many respects a separate war in itself. The first two years of the war (1618-20) is occupied with the Bohemian revolt against the attempt of the Emperor to force Catholicism upon the Bohemian people and with its immediate consequences. It was accentuated by the attempt of the Emperor Matthias to compel them to accept the Archduke Ferdinand as King. This attempt was countered through the election by the Bohemians of the Pfalzgraf, Friedrich V (the son-in-law of James I of England), who was called the Winter King from the fact that his reign lasted only during the winter months; for though the Protestant Union, led by Count Thurn, had won several victories in 1618 and even threatened Vienna, the Austrian power was saved by Tilly and the Catholic League which came to its rescue. Many of the Protestant States, moreover, were averse to the Palatine Friedrich's acceptance of the Bohemian crown. The Bohemian movement was ultimately crushed by a force sent from Spain, under the Spanish general Spinola. The final defeat took place at the battle of the White Hill, near Prague, November 8, 1620. The second period of the war was concerned with the attempt of the Catholic Powers to deprive Friedrich of his Palatine dominions. Here Count Mansfeld, with his mercenary army of free-lances, aided by Christian of Brunswick and others on the side of Friedrich and the Protestants, defeated Tilly in 1622. But later on Tilly and the Imperialists by a series of victories conquered the Palatinate, which was bestowed upon Maximilian of Bavaria. Mansfeld, notwithstanding that he had some successes later in the year 1622, could not effectually redeem the situation, Brunswick's army being entirely routed by Tilly in the following year at the battle of Stadtlohn, which virtually ended this particular campaign.