Schroeder’s major work was The Transformation of European Politics 1763–1848, which he published in 1994. His first book, The Axis Alliance and Japanese-American Relations 1941 (1958), based on his master’s thesis, was a study of the two Pacific hegemons and the lead-up to the attack on Pearl Harbor. This was followed up by Metternich’s Diplomacy at Its Zenith, 1820–1823 (1962) and Austria, Great Britain, and the Crimean War (1972). The Transformation of European Politics, a monumental work of over 900 pages, would be his last monograph. Schroeder would spend the next decade and a half, until his death in 2020, writing essays and articles intervening in scholarly and political debates.

Many historians and social scientists examine wars as exceptions or catastrophes, breakdowns whose origins must be studied to prevent them in the future. Schroeder’s insight was to flip this commonplace stance on its head. For him, the question was not why did wars occur, but rather, why did peace persist? War, he argued, was in fact the natural state of relations between states. It was the condition to which state relations tend in the absence of any countervailing force. It is peace that is unnatural.

Yet somehow, peace, or at least the avoidance of great power conflict, has been possible in the past. Schroeder’s central example of a former period of peace was the nineteenth century in Europe. Between Napoleon Bonaparte’s defeat at Waterloo in 1815 and the Franco-Prussian War in 1870, Europe enjoyed a period of relative calm. This long peace was thanks largely to the Concert of Europe, a complex agreement between the continent’s great powers that acknowledged the existence of spheres of influence. It produced what came to be known as the Vienna System, a remarkably stable order that came under severe strain in the last decades of the nineteenth century before imploding dramatically in 1914. Stealing Horses is essentially an autopsy of this system, written with calm and analytical rigor.

In recognizing that peaceful coexistence between nations was not just a possibility but also a primary activity of statecraft, Schroeder distinguished himself from the pessimistic conservative tradition associated with Thomas Hobbes. This is a tradition that views the international realm as a global state of nature in which nations face off against one another in a war of all against all. He made no attempt to deny the reality of the state of nature, but he insisted that humans could organize in ways that could eliminate or reduce the threat of violence.

The long peace that became the subject of Schroeder’s last book took its name from the Congress Vienna. There global leaders took stock of the post-Napoleonic world and sought to create new forms of state relations that would prevent an outbreak of another conflagration. The great powers desperately wanted to avoid the return of a period of instability like that that had wracked the continent from 1789 to 1815. While the peace at which the negotiators arrived was enduring, it was far from stable.

The Vienna System went through a series of life cycles. Its high point was the period between 1815 to 1848, after which the system underwent a number of challenges, from the Crimean War in the 1850s to German unification in 1871. The system then hobbled on through to the 1890s before suffering a fatal paroxysm in the summer of 1914. While this peace was far from perfect, Schroeder argued that it was a fundamentally new development in European politics since the formation of the early modern state system in the seventeenth century.

Schroeder was quick to acknowledge that the maintenance of peace is not the same as the end of competition and conflict between states. The Vienna System functioned as well as it did precisely because it did not eliminate all friction between states. Rather it worked to channel and mediate this friction. To do so, the system devised new rules for conducting diplomatic relations, established a form of international law, ensured that ambassadors and aristocrats held conferences and congresses to broker deals, and maintained a general consensus for the need to create compromise and coalitions to determine territory and also to isolate states that broke these conventions.

In practice, this meant reducing the influence of France and preserving the Habsburg Empire as a buffer against the conflicting ambitions of Prussia, Russia, and the Ottoman Empire within Central Europe, while also reining in the desire of small states for territorial aggrandizement. The Greek Revolution of 1821 was a proving ground for the new balance of power logic. There the great powers acted to prevent Russian intervention, which would have provoked an Ottoman response and thereby a general war in Eastern Europe and the Balkans. This peace was not, however, without cost. It was bought through the suppression of liberal nationalist reformers by what amounted to an international anti-revolutionary alliance.

One of the central pillars of Schroeder’s outlook is what he termed “negative Austrophilia.” What this meant was a pragmatic acceptance of the need for a unifying state in the region of Central Europe, the area that was taken up by the Habsburg Empire. This was not a position he arrived at out of sympathy for the ancien régime. Rather he believed that without such a state in the region the potential for violent conflict could only increase. The maintenance of the Habsburg Empire prevented the creation of a vacuum into which the surrounding empires would rush, inevitably producing conflict. Negative Austrophilia stands in for a broader geopolitical principle. This is that buffer states and mediating areas between great powers are necessary to both lessen the ambitions of strong states and to reduce the likelihood of them coming into conflict with one another.

What motivated Schroeder’s support for negative Austrophilia was a belief that order rather than justice was the guiding principle for any international state system. This was a classical conservative position borne out of fear that utopian demands for redress could only further violence and instability. Though the Habsburg Empire was a flawed state by most metrics, for Schroeder the important thing was not to overthrow or remove states that are imperfect, but rather to operate with a realism about the potential political vacuum that a state can hold at bay by its existence. Summed up in a phrase, Schroeder’s philosophy was essentially: better the devil you know.

Schroeder’s studies of the Vienna System came to influence his view on contemporary US politics, particularly in the post–Cold War era. In his view, the height of American hegemony was at a period in which the United States worked to destroy the postwar order that had propelled it to primacy. As a conservative concerned with stability, he found the hubris of US foreign policy exasperating and became an unlikely, but unwavering, critic of his country’s imperial efforts after the Cold War. In this respect, Schroeder bears comparison to Andrew Bacevich, another conservative who grew disenchanted with the myopia of his conservative interlocutors.

Schroeder often referred in his writing to a quip attributed to Klemens von Metternich that the aim of politics was to “outlive the evil.” By this, he meant that a key rule for great powers like the United States was to not use its military force to crush its enemies or to seek out conflict in order to solve perceived problems. Rather the US should aim to ensure “that one’s own values, institutions, and way of life survive and ultimately thrive while those who would overthrow them are gradually marginalized and ultimately die out.” The aim of grand strategy was, in his view, to create a system based around assured benefits and inclusion — sticks rather than carrots. The penalty for states that sought to destabilize the system or that went against its rules was not to be crushed, but rather to be excluded from a beneficial relationship. This assured that stepping out of line would always be an act of self-harm.

Maintaining such a system requires transcending short-term political interests; statesmanship was, in Schroeder’s view, essentially a moral project concerned not with furthering justice but with constraining one’s own impulses for the stability of the system as a whole. The ability to exercise this level of prudence is a product of “collective historical learning” borne out of tragedy and crisis.

If stability was a product of historical learning, then the process of historical forgetting for the United States in the post–Cold War era set in well and truly during the invasion of Iraq in 2003. Schroeder considered this intervention an instance of straightforward imperialism. Its effects on the international state system were, he argued, disastrous. Schroeder characterized this breakdown as a “fatal leap” from hegemony — by which he meant occupying the position of “first among equals” — to empire. It was effectively a shift from paternalistic rule in the interest of other states to direct rule over them.

What lessons should we draw from Schroeder’s writing today? Clearly the breakdown of the Vienna System bears comparison to the breakdown of the American-led postwar order currently being enacted by Donald Trump. Throughout the second half of the twentieth century, the United States maintained global hegemony after World War II by offering security guarantees to Europe, making itself the consumer of last resort for all the world’s largest economies, and by establishing the dollar as the global reserve currency. These were the foundations of American power, but they could just as well prove to be the basis of its undoing.

In Schroeder’s most influential essay, “World War I as Galloping Gertie,” the Galloping Gertie of the title refers to a suspension bridge that was built across the Tacoma Narrows, a strait in the Puget Sound in the state of Washington. The bridge collapsed on November 7, 1940, just over five months after it had first opened. Under unforeseen pressure, the structures that had been meant to hold the bridge up buckled under pressure caused by high winds. These winds created vibrations that the structure could not handle. The bridge twisted and swayed in ways that it was not designed to withstand and eventually the suspender cables collapse. This accident was, in Schroeder’s imagining, a metaphor for the collapse of the international state system in the years leading up to World War I: “the very devices built into a system to keep it stable and operative under stress, subjected to intolerable pressures, generate forces of their own which cause the system to destroy itself.” Since the end of the Cold War, the United States has undergone its own Galloping Gertie moment. What had previously maintained US hegemony is now working dramatically to undermine it.

One of the key pillars of US hegemony in the post–Cold War era has been close economic ties with China and the willing cooperation of Europe. Trump is now attempting to abandon hegemony in favor of a model in which the relationship between the United States and other states is that of vassalhood. Schroeder’s writing makes it easy to imagine why such a move is likely to end in disaster but also what an alternative might look like.

This would be a model of world affairs managed through a global troika of the US, the European Union, and China. What is so worrying about Trump’s policies is that they seem to have been designed primarily with the aim of preventing the emergence of these poles. With his reckless tariffs, he has undermined Europe’s support for the United States while simultaneously increasing hostilities between America and China. Can the US, by itself, reorder the global system? This seems highly unlikely. What America can do, however, is bring the whole system crashing down.