A soldier at heart from his earliest childhood, Rupert did not remain long at Leyden, but entered the army under Henry Frederic of Nassau, and (Lodge tells us) was present at the siege of Thynberg, although another biographer places the date of his first action several years later. Be this as it may, in 1637 he marched with his brother, Charles Louis, who now called himself Elector Palatine (their father being dead), against the Imperialists. The gallant Lord Craven had constituted himself the guardian of 'the Palatine Princes,' and accompanied them in the expedition, writing frequently to their mother at the Hague, to give tidings of Charles and the beloved Rupert. Lord Craven had warmly espoused the cause of Frederic, and was now the devoted friend of the royal widow and her family. He and his two charges distinguished themselves during the siege of Lippe, but being worsted in an encounter with General Hatzfeldt, Charles Louis had a narrow escape of his life. He crossed the river in his coach, and, clinging to the shrubs and underwood, climbed up on the precipitous bank of the opposite shore, and made his way to Holland. His brother and Lord Craven were both taken prisoners by the Imperialists, and carried to Vienna, where they were lodged in the castle. With much difficulty Rupert found means to have a few lines conveyed to his mother, wherein, after some tender expressions of filial love and respect, he assured her that no power on earth should induce him to renounce his party, or abjure his faith. Lord Craven succeeded in regaining his freedom, by paying the large ransom of £20,000; but all attempts to procure the deliverance of Rupert proved unavailing. It was only at the expiration of three years, and on condition that he would undertake never again to bear arms against the Emperor, that the young Prince was set at liberty, shortly after which event he received an offer from his uncle, Charles the First, of the command of the cavalry in the
