PHILIP, LANDGRAVE OF HESSE (1504-1567), son of the land grave William II., was born at Marburg on Nov. 13, 1504. He became landgrave on his father's death in 1509, and having been declared of age in 1518, was married in 1523 to Christina, daughter of George, duke of Saxony. In 1522 and also in 1523 he assisted to quell the rising of Franz von Sickingen (q.v.), who had raided Hesse five years previously, and in 1525 he took a leading part in crushing the rebellion of the peasants in north Germany, being mainly responsible for their defeat at Frankenhausen. About this time Philip adopted the reformed faith. His plans to protect the reformers rested upon two main principles—unity among the Protestants at home and military aid from abroad. The schemes he put forward as one of the heads of the league of Schmalkalden, aimed primarily at overthrowing the house of Habsburg. Envoys were sent to seek aid from France, England and Denmark; Turkey and Venice were looked to for assistance ; the jealousy felt towards the Habsburgs by the Bavarian Wittelsbachs was skilfully fo mented.
Before the formation of the league of Schmalkalden Philip was intimate with Zwingli. In 1526 he had aided John the Constant, elector of Saxony, to form an alliance of reforming princes; and in 1529 he called together the abortive conference at Marburg, hoping thus to close the breach between Lutherans and Zwinglians. Deceived by the forgeries of Otto von Pack (q.v.), he believed in the existence of a conspiracy to crush the reformers, and was only restrained from attacking his enemies, in 1528, by the influence of John of Saxony and Luther. In 1529 Philip signed the "protest" presented to the diet at Spires, being thus one of the original "Protestants"; in 153o he subscribed the Augs burg confession, and helped to form the league of Schmalkalden.
He next restored Ulrich, duke of Wiirttemberg (q.v.) to his duchy. Wiirttemberg had passed into the possession of the Habs burgs, and after Philip's brief and victorious campaign in it was said that the landgrave had done more for Protestantism by this enterprise than a thousand of Luther's books would do. The Concord of Wittenberg, made in 1536, was preparatory to a general attack on the Habsburgs, but war was prevented by the ill ness of the landgrave and other circumstances. At this point he took a fatal step. His union with Christina was unhappy, and, having fallen in love with Margaret von der Saal (d. 1566), he obtained an opinion from Protestant theologians that bigamy was not forbidden by Holy Writ. Luther and Melancthon at length consented to the marriage, but stipulated that it should be kept secret, and it was celebrated in March 154o. The marriage be came known, and Philip's friends deserted him. He objected to Luther's counsel to deny the existence of a second marriage. But the general hostility compelled Dim to come to terms, in 1541, with Charles V. at Regensburg; he undertook to break off relations
with France and England and loyally to support the emperor.
From 1526 onwards Philip had been forwarding the progress of the Reformation in Hesse. Catholic worship was suppressed, and the secularized church revenues supplied an endowment of the new university of Marburg. Peace between the emperor and the landgrave was soon broken. In 1542 Philip persuaded the league of Schmalkalden to attack Henry II., duke of Brunswick Wolfenbiittel, ostensibly in the interests of the Protestant towns of Brunswick and Goslar. The duchy was quickly overrun, and Henry—a Catholic prince—driven out ; but the good understand ing between the emperor and the landgrave was destroyed, and the relations between Protestants and Catholics became worse than before. Nor was the fissure in the Protestant ranks closed, and Charles took advantage of this disunion to conquer Gelderland and to mature his preparations for overthrowing the league of Schmal kalden. Unlike John Frederick of Saxony, Philip divined, or partly divined, the emperor's intentions, and urged repeatedly that the forces of the league should be put in order. This advice passed unheeded, and when Charles suddenly showed his hand, and in July 1546 issued the imperial ban against the landgrave and the elector, it was seen that the two princes were almost isolated. Fighting began along the upper Danube, and when indecision and want of funds had ruined the league's chances of success, Philip returned to Hesse and sought help from foreign powers ; while in April 1547 John Frederick was captured at Miihlberg. After this defeat the landgrave was induced to surrender to Charles in June by his son-in-law, Maurice, now elector of Saxony, and Joachim II., elector of Brandenburg, who promised Philip that he should be pardoned, and were greatly incensed when the emperor refused to assent to this condition. Philip was sentenced to detention for I5 years, but he was released in 1552, and after the Peace of Passau in this year he returned to Hesse. The landgrave con tinued the work of reforming and organizing the Church in Hesse. In 1562 he aided the Huguenots with troops, and he was frequently in communication with the insurgents in the Netherlands; but his efforts to form a union of the Protestants were fruitless. Philip, who is sometimes called the Magnanimous, died at Cassel on March 31, 1567.
See Briefwechsel Landgraf Philipps mit Bucer, ed. M. Lenz (Leipzig, 1881-90) ; Politisches Archiv des Landgrafen Philipp, ed. F. Kdch (Leipzig, 1904) ; W. W. Rockwell, Die Doppelehe des Landgrafen Philipp von Hessen (Marburg, 1904) ; K. Varrentrapp, Landgraf Philipp von Hessen und die Universitat Marburg (Cassel, 1904) ; and Philipp der Grossmiitige, Beitrage zur Geschichte seines Lebens und seiner Zeit, published by the Historischer Verein fur das Grossherzog tum Hessen (Marburg, 1904)