succeeded by Mathias. Thus Mathias succeeded to the Archduchy in 1608, and became emperor in 1612, until his death in 1619. His reign was marked by conflict with his younger brother Maximilian III who was a more intransigent Catholic and backed the equally fervent Ferdinand II of "Inner Austria" as successor, having served as his regent between 1593 and 1595, before taking over "Upper Austria". The conflicts weakened the Habsburgs relative to both the estates and the Protestant interests. Mathias moved the capital back to Vienna from Prague and bought further peace from Turkey, by a treaty in 1615. Meanwhile, religious fervor in the empire was mounting, and even Klesl by now Bishop of Vienna (1614) and Cardinal (1615) was considered too moderate by extremist Catholics, including Ferdinand II. War was in the air, and the assault on two roral officials in Prague on 23 May 1618 (The Defenestration of Prague) was to spark all out war. Mathias, like his brother Rudolf, became increasingly isolated by Ferdinand who had imprisoned Klesl. The next brother in line for succession in 1619 was Albert VII, but he was persuaded to step down in favour of Ferdinand II within a few months. Reformation and Counter-Reformation Religion played a large part in the politics of this period, and even tolerance had its limits faced with the incompatible demands of both camps. As the Archduke closest to the Turkish threat, Maximilian II was to continue his father's policy of tolerance and reconciliation, granting Assekuration (legalisation of Protestantism for the nobles) in 1571, as did Charles II with Religionspazifikation in 1572, while in distant Tyrol, Ferdinand II could afford to be more aggressive. Maximilian II's policies were continued by his sons, Rudolf V and Mathias. The strength of the Reformation in Upper Austria was blunted by internal schisms, while in Lower Austria Melchior Khlesl led a vigorous Catholic response, expelling Protestant preachers and promoting reconversion. A further concession by Charles II in 1578, the Brucker Pazifikation, met with more resistance. The Catholic Revival started in earnest in 1595 when Ferdinand II, who was Jesuit-educated came of age. He had succeeded his father, Charles II in Inner Austria in 1590 and was energetic in suppressing heresy in the provinces which he ruled. Reformation Commissions initiated a process of forced recatholicisation and by 1600 was being imposed on Graz and Klagenfurt. Unlike previous Austrian rulers, Ferdinand II was