Anselm Casimir, archbishop-elector of Mainz, is not usually counted among the leading protagonists of the Thirty Years’ War. On one level, Franz Brendle's 2008 Habilitation delivers what one expects from a conventional political biography, buffing up the reputation of his protagonist and demonstrating his considerable talents and perspicacity. Anselm Casimir's career is followed chronologically, with brief coverage of his Jesuit education and rise through the ranks of the Catholic clergy in the Holy Roman Empire to the top job in Mainz, placing him formally as second only to the emperor by 1629. In charting Anselm Casimir's involvement in the key political events of the war, Brendle identifies three guiding principles of his policy. The archbishop remained a political moderate throughout, distinguishing between his own subjects, who were expected to be good Catholics, and the princes and other powerholders in the Empire with whom Anselm Casimir was prepared to deal regardless of confession, provided that they respected the imperial constitution. Here, Brendle makes an important contribution to early modern German history by demonstrating that this political moderation was firmly established in Mainz well before the accession of Anselm Casimir's more famous successor, Johann Philipp von Schönborn. The real difference between the two archbishop-electors lay in their attitude towards France. Schönborn owed his election to French influence, whereas Anselm Casimir rejected offers of a French alliance during the war as contrary to his duty to the Empire and his desire for a negotiated peace. Loyalty to the emperor formed the third plank of his policy, but was far from blind obedience as demonstrated by Anselm Casimir's opposition to the imperial general Wallenstein whose precipitous rise threatened the traditional constitutional order. These are all important findings, but where the book really succeeds is by giving a clear and lucid insight into the complex interaction between religion and politics during the war. Brendle deftly demonstrates the range of opinion amongst Catholics concerning the pursuit of religious goals by violent means. This question was directly relevant to the Catholic ecclesiastical princes and hinged on the relative weight of their twin duties to preserve peace and safeguard the German church lands. Militants stressed the latter, arguing that the threat to souls was greater than that to bodies and required Catholics to fight on regardless of the material and human cost. Anselm Casimir championed the former course, stressing the Christian duty towards neighbours and arguing that the war was harming Catholicism by preventing clergy from tending their parishioners. Brendle suggests that the war's outcome promoted secularisation in the longer term by discrediting militant Providentialism. Calls to resist at all costs had merely prolonged the misery without bringing the hoped-for divine favour. Anselm Casimir died a year before the conclusion of the peace negotiations to which he made a substantial contribution.