Emerging out of the splendid Princeton tradition of interest in power and the economy, this book examines the railroad industry in Germany in terms of how technology affects power. In a very general sense, this book builds on two important genres: the work of Aaron Friedberg on the decline of British power, the “garrison state” notion associated with the United States, and the industrial rise of China; and the seminal work of Robert Gilpin regarding French nuclearity and of Klaus Knorr on the economic determinants of war potential. Although the final chapter has useful things to say about the digital revolution and its impact on contemporary security, the heart of the analysis is the treatment of the German railroad industry. The strength of this book is that its historical case study is informed by crucial questions drawn from the field of international relations. Hence, the book is far more useful to students of international relations than if it were a mere historical monograph.

Geoffrey Herrera argues that the railroad transformed the German state politically, shaped its security and its foreign policy aspirations, and catalyzed the growth of its economy. In terms of space, the railroad united the disparate parts of the German principalities under the iron fist of Prussia. In terms of time, Germany did more with the railroad, faster, than anyone else in Europe. It is without question that while Britain was the locus of most of the innovation in engine and rail, the growth of the railroad was much faster in Germany, as “second mover,” than in Britain. At the end of the first decade of German railroad expansion in 1845, Germany had built 2,143 kilometers of track to Britain's mere 544 kilometers.

The diffusion of technological ideas (as reflected in distinctive studies by Randolph Siverson, Harvey Starr, Benjamin Most, or William Thompson) is a fascinating topic about which Herrera has something to say. The author points out, for instance, that once the railroad was under construction in Britain, only about 10 years were required for these ideas fully to spread to Germany. His contribution, however, is limited by the fact that he tends to address the topic of technological diffusion more than a particular theory of international politics.

Moreover, in this reader's view, the connection Herrera sees between rail growth and security may have been less straightforward than he would have audiences believe. I would argue that Germany practiced an import substitution policy of economy growth, following the precepts of theorists such as Friedrich List, a great advocate of railroad construction who totally misjudged its effect on security, thinking that such a revolutionary technology would make war obsolete. Nevertheless, it is unclear whether Germany was capital poor and government dominated because it employed an import substitution strategy, or whether Germany was forced to follow a dirigiste strategy because it failed to produce much of an entrepreneurial middle class in the nineteenth century. Expansion of the railroad could provide food for either thesis.

A further issue is whether the impact of technology such as the railroad on national power is truly considered in the relative sense. Multiple governments benefited from railroad development. Therefore, in order to speak of the impact of the railroad on one state's power, researchers must control for the impact on the power of the other states, especially rivals. This study is conscious of this problem but does not always systematically apply the lessons of relative technological impact to discussions of state power.

Herrera argues that from the start, military-strategic considerations governed German decision making with regard to railroad planning. Some of those calculations proved valid. Others did not. Inside a state surrounded by hostile neighbors, military planners sought assurance that they could get their armies to their borders quickly, and so they did by investing in rails/railway technology. But as a component of the infamous Schlieffen Plan for a two-front war, the German railroad system proved far less effective. A number of explanations emerge from material supplied in this book.

First, as an element of military strategy, the railroad had to compete with the capacity of neighbors, in this case in particular France, to use their own railroads for the same purpose. Second, once the capacity of the railroads to move large numbers of troops quickly for offensive purpose was understood, defensive techniques to make the railroad inoperable through the destruction of tracks, bridges, and tunnels very much constrained the offensive contribution of rails, especially outside domestic territory. Third, each railroad contained its own vulnerabilities and its own strengths. Planning with respect to coordination and load capacity was even more important than were some aspects of infrastructure per se.

Hence, the fine German railroad system, carefully designed for military-strategic purpose as well as commercial use, was a great help in defeating the somewhat larger French army in the Franco-Prussian War (1870–71), especially when Chief of Staff Helmuth von Moltke used it to help outflank the French army at the beginning of the war, and prior to the German army's getting bogged down in Paris near the end of the war. But, Herrera rightly points out, the German railroad proved much less of a unilateral advantage by the time of World War I. Readers are led to conclude that technology possesses a one-sided advantage only for a comparatively short period of time, namely, until it generates its own countertechnology and strategies.

Overall, the strengths of this book lie in the way it explores the relationship between technology and military power. The relationship of either technology or industrial development to the analysis of the international system is less developed than readers (of its title) might initially suppose. In other words, the richness of the book is in Herrera's assessment of how technology enhances power internal to the state, its economy, and its defenses, rather than how technological innovation affects relations externally in the larger international system. Although some attempt is made to examine the railroad in other countries and in the colonies, such as in South Africa and India, by far the greatest contribution is in understanding the relationship of technology to power inside Germany.

Likewise, although the author, unlike his mentors, develops neither a theory of international politics nor analysis based on hypotheses, systematic quantitative research, and causal interpretation, his contribution of this analysis to international political economy and to security analysis is substantial. More than history, this analysis raises many strategic and developmental questions that find at least partial resolution in the data and discussion presented.

In particular, this book is a prototype for comparative foreign policy. Herrera touches on useful contrasts and comparisons between Germany and Britain, for example, and between Germany and the United States (this is at least begun here regarding the development of the atom bomb), that are full of rich possibilities for future research. Students of comparative foreign policy should find Herrera's work a good start for looking at other contrasting technologies and industries to determine how they affected the respective foreign policies.

Indeed, at the end of the day, analytically, an examination of the impact of technological change on power must itself be grounded in a firm grasp of what relative power is, and what it connotes across time and within a systemic context.