This extensively researched book proves that we cannot understand the Holy Roman Empire in the sixteenth and seventeenth centuries unless we appreciate the centrality of corporate alliances (often called leagues) among princes and cities. Such alliances—like the impressive Swabian League and the unfortunate Schmalkaldic League—directed imperial politics and sometimes functioned as the empire's military. Christopher Close offers an impressive and convincing new historical paradigm of political change in early modern Germany.

Close explains in his introduction that a historiographical fixation on “bureaucratic institutions as the main vehicle for state formation” has resulted in a neglect of institutions of shared sovereignty like corporate alliances (4). Setting out to correct this oversight, Close tells a fascinating story about the many corporate alliances of the sixteenth and seventeenth centuries, including lesser-known ones like the Nine Years League and the League of Landsberg. He begins in Chapter 1 with the Swabian League, which was not only “one of the most effective fighting forces of its time” but also “the most visible embodiment of the ideals of public peace and collaborative action that many Estates saw as the basis of the Empire's constitution” (54). Close provides the best analysis of the Swabian League currently available in English. He pays special attention to the league's Rezeptionsgeschichte and uncovers the league's impact on German politics well after its dissolution.

Chapters 2 and 3 examine the impact of the Reformation on Germany's politics of alliance. Close offers an absorbing account of how confessional solidarity warped the political sinews of the empire. Regarding the impact alliances had on religious reforms, Close makes a bold claim: “The operation of overlapping and sometimes opposing leagues during the early Reformation produced complex webs of alliance that shaped how the Reformation spread, where it put down roots, and how Estates conceptualized the role of religion in the Empire's political life” (57). He supports this claim with an impressive analysis of Protestant, Catholic, and cross-confessional alliances—with a special focus on the Schmalkaldic League—and even finds that alliances pioneered “a language of religious coexistence” remarkably similar to the famous maxim cuius regio eius religio (97). For example, the Union of Utrecht owed its longevity, partly, to its “‘live and let live’ policy concerning multiple Christian confessions” (207).

Chapter 4 studies the League of Landsberg and its role as an arbiter and police force in the years after 1555. Chapter 5 juxtaposes the League of Landsberg and the Union of Utrecht, with the goal of correcting a historiographical deficiency Close describes thusly: “While many studies of the Low Countries discuss the Union of Utrecht, the historiography does not place the Union in the wider context of northern European politics of alliance” (169). Close moves beyond the usual national framework of historical inquiry and helps his reader understand the Union of Utrecht as part of a wider political tradition in the Holy Roman Empire.

Chapters 6 and 7 tackle the Protestant Union and the Catholic League in the years leading up to the Thirty Years’ War. Close contextualizes famous events like the War of the Jülich Succession and the Bohemian Revolt within the broader history of alliances and convinces his reader that the course of the Thirty Years’ War “hinged on the interplay of closely related religious and constitutional impulses filtered through the politics of alliance” (248). Chapter 8 returns to the Low Countries and shows how the Holy Roman Empire's politics of alliance survived the Thirty Years’ War and became an essential component of Dutch state formation.

The great strength of Close's book is the way he connects the major events of the era to the politics of alliance. By studying this mezzo-level of politics above individual estates and below the empire at large, Close offers fresh new explanations for anomalies like the Truce of Nuremberg as well as for trends like the cautious implementation of the Reformation in southern German cities. Close contributes to an exciting new historiography—along with Duncan Hardy, Hendrik Baumbach, and others on both sides of the Atlantic—that reevaluates the corporate nature of the Holy Roman Empire.

Regarding state formation, Close shows that corporate alliances were essential for the formation of the Dutch state. But he does not convince this reader that corporate alliances, though dominant in the early modern era, powered state formation in Germany. Alliances may have “shaped the process of state formation” (44), and “impulses from corporate alliances both realized and unrealized” (134) may have influenced the development of states, but only indirectly and usually as impediments to bureaucratization and centralization. Admittedly, Close does not aim to explain the origins of central bureaucracies in Germany and instead seeks to illuminate how early modern states—as defined by Matthias Schnettger and Michael Martoccio—functioned. He accomplishes this goal and provides his reader with a fascinating study of early modern alliances in the Holy Roman Empire.

Close's study is an essential read for historians of the Holy Roman Empire and the Reformation. His meticulous consideration of alliances and military campaigns demands the attention of diplomatic and military historians, even those focused on modern Europe. State Formation and Shared Sovereignty has the potential to draw the attention of such historians back to the sixteenth century. Close puts alliances at the heart of Central European history and shows that we cannot understand early modern Germany or the Netherlands without understanding these dynamic institutions.