Andreas Stegmann's study of the Reformation in the Mark Brandenburg offers a fascinating insight into the practical politics of the introduction of Protestantism in an interlocking complex of early modern territories. Stegmann begins by presenting the situation of the medieval Church in the Mark Brandenburg, with particular focus on the relationship between the territorial ruler and the bishops of the three dioceses within which the Mark lay, and outlining the elector's attempts, from the mid-fifteenth century, to introduce unified ecclesiastical structures into his territory, effectively creating a pre-Reformation Landeskirche. After a short consideration of the beginning of the Reformation in Germany, Stegmann returns to Brandenburg: he presents the efforts of Elector Joachim i, brother of Archbishop Albrecht of Mainz, to resist the Reformation even as other Hohenzollern rulers introduced it (thus Margrave Albrecht of Brandenburg was an early supporter of Luther and introduced the Reformation in Prussia), his wife the Danish-born Elisabeth of Brandenburg became convinced by Luther's teachings, and Reformation ideas also grew in popularity amongst his subjects. After Joachim i’s death in 1535, his sons, Elector Joachim ii (1505–71; ruled 1535–71) and John, margrave of Brandenburg-Küstrin (1513–71; ruled 1535–71), both introduced the Reformation into their territories. Stegmann shows how Margrave John's freedom to act in religious questions was much greater than his brother's: as an Elector, Joachim's actions were more carefully scrutinised, and he was under considerable pressure both within the Holy Roman Empire and from his father-in-law, the king of Poland, to remain Catholic. In contrast, as a less significant political player, Margrave John was able to introduce the Reformation and join the League of Schmalkalden without attracting such negative attention. None the less, from summer 1539, Joachim ii introduced the Reformation into Brandenburg in three stages: first, he allowed the appointment of Lutheran, evangelical preachers; at All Saints 1539 the Lord's supper was celebrated in place of the mass, with a German liturgy and communion in both kinds; and in 1539/40 a series of visitations took place assessing the state of parishes and valuing their property. A church order was drafted and printed in 1540, laying out the faith to be taught from henceforth in Brandenburg; drawing on contemporary Protestant church orders, but also on medieval liturgical books, it included the necessary liturgical rites, now in German, and defined the structure of the Church. The Brandenburg church order was endorsed by the bishop of Brandenburg, and Joachim ii hoped to keep the episcopal structures of the Church, integrating them into the new Landeskirche. In letters to his father-in-law he presented these reforms as reforms of the Catholic Church. However, the bishops of Havelberg and Lebus refused to recognise the new Brandenburg church order, and a parallel structure of superintendents and a consistory emerged to replace them. Stegmann considers the further development of these structures through the period of the Schmalkaldic Wars and the Peace of Augsburg until the deaths of Joachim ii and Margrave John in January 1571. He offers a discussion of developments in the seventeenth century, before closing with a consideration of Reformation anniversaries and historiography in the nineteenth and twentieth centuries. Stegmann here provides a fine addition to the growing series of territorial studies of the German Reformation. His study draws on meticulous research to show vividly the complex processes which led to and accompanied religious change and Reformation.