Declaring War in Early Modern Europe by Frederic J. Baumgartner (review)

Declarations of war have been the subject of intense debate over the past decade. The process of initiating the Iraq War in 2002–2003 reawakened wounds in American political culture over the legal and constitutional ramifications of commencing warfare without a declaration of war.

The United States has a long history of initiating armed conflict without the U.S. Congress issuing a formal declaration of war, as required by article 1, section 8 of the Constitution of the United States. The fledgling United States engaged in warfare in the Quasi War of 1798–1800 and the Barbary War of 1801–1805 without actually declaring war. The United States fought against Amerindians, Filipinos, Chinese, Latin Americans, and other peoples in the context of imperial expansion and colonization in the nineteenth and early twentieth centuries despite the lack of an official declaration. The 1907 Hague Convention and the 1945 United Nations Charter both seemed to close legal questions on the legitimate practice of warfare among states, but the United States later waged conventional and counterinsurgency warfare in the Korean and Vietnam Wars without ever issuing a declaration. The War Powers Resolution of 1973 was intended to resolve the constitutional issue of who has the legitimate authority to instigate military action in the United States. But the Vietnam experience also left lasting legacies of bitterness and confusion over war powers that have only been deepened by the recent debates over the prosecution of the Iraq War and Afghan War.

Frederic J. Baumgartner’s Declaring War in Early Modern Europe responds to these issues, providing historical perspectives on the legal theories, state practices, and ritualistic formalities of declaring war from the sixteenth century to the Napoleonic period. Baumgartner also offers a brief survey of the ancient and medieval history of declaring war, which shaped the early modern legal discourses on just war and the law of war.

Baumgartner identifies three leading theories on the power to declare war: categorical, pragmatic, and formalist (p. 3). Categorical theories limit war powers to an authority that holds complete control to engage in war. Pragmatic theories allow war powers to be exercised without declaring war, but only if the nation is attacked. Formalist theories allow all war powers short of total war to be exercised without declaring war. After briefly explaining these current theories, the book investigates the relevance of the early modern historical contexts for evaluating these theories’ usefulness.

Ancient societies developed complex rituals for initiating war that continue to shape modern understandings of war. “The act of declaring war,” according to the author, “was transformed from a magical process to one entirely conventional, although the proper performance of the act was still seen as conveying divine approval of the coming war” (p. 7). The Roman practices of using fetial priests to declare war provide a key case in Baumgartner’s analysis, which suggests that Roman rituals continued to influence medieval practices despite considerable variation and evolution.

Medieval legal theorists considered the jus ad bellum (law on initiating war) as largely established, whereas the jus in bello (law on the practices of war) were much debated. By the late fourteenth century, Baumgartner argues, “wars of self-defense could be waged by anyone, but only a prince who had no sovereign could declare a just war of aggression” (p. 27). Medieval princes often used heralds to issue their declarations of war by reading letters of defiance or unfurling a flag of war.

The heart of the book concentrates on the new theories and practices of warfare that reshaped declarations of war in the long sixteenth century. The author delves especially into the French, English, and imperial declarations of war in the period of the Italian Wars (1494–1559) and European Wars of Religion (1562–1660). With the advent of the printing press, declarations of war increasingly incorporated printed challenges and grievances that served as propaganda. Baumgartner draws attention to the legal theories of Renaissance humanists such as Desiderius...