Kaiser Wilhelm II
Kaiser Wilhelm II; drawing by David Levine

Kaiser Wilhelm II was an emblem of his era. Modern in his appreciation of the power of the media, hungry for publicity and adulation, he was constantly in the news, whether celebrating with his royal English and Russian cousins or inaugurating local railroad stations and monuments. Articulate and garrulous, the kaiser broadcast remarks that became instant catchphrases, especially those that escaped the censorship of his handlers, such as his claim that “the ruler’s will is the public law” or his favorable comparison of German soldiers to “Huns.” His ubiquity earned him the name “Reise-Kaiser” (the traveling emperor). He was also impetuous, flighty, and hard to control—“Wilhelm der Plötzliche” (Wilhelm the Sudden). Even his aggressively upright mustache acquired an epithet: “Es ist erreicht!” (It is achieved!)

On June 28, 1914, Bosnian-Serb students who chafed at Austria’s repression of Serbian nationalism in its empire assassinated the heir to the Austrian throne, Archduke Franz Ferdinand. Wilhelm responded to the death of his royal friend by pressing for war. Two days later, he noted in the margin of a diplomatic telegram that it was “now or never.” On July 5, he assured the Austrian ambassador that Germany would support Austria’s retaliation against Serbia even if it ignited a continental war against Serbia’s ally Russia (and Russia’s ally France).

The kaiser’s resolution was uncharacteristic. In previous crises, he had either scotched the warlike plans of his advisers (for example during the Moroccan Crises of 1905 and 1911) or they had had to stir up his enthusiasm, as in the late autumn of 1912 during the First Balkan War. In the latter instance, he eventually went beyond their intentions, demanding in effect a world war, but then pulled back when naval leaders complained that they were unready to take on England.

In the July Crisis of 1914 he wavered again, despite his initial resolve. Austria delivered a harsh ultimatum to the Serbs that demanded vast interference in Serbian domestic affairs. It was designed to be rejected and thus offer cover for an Austrian invasion. Serbia’s clever reply seemed to submit to the terms with a few reservations. The kaiser then declared on July 28 that “all ground for war has vanished.” Chancellor Theobald von Bethmann Hollweg and Chief of the General Staff Helmuth von Moltke manipulated the reluctant monarch back to bellicosity. Without royal approval, Germany could not have begun the war. On the first anniversary of its outbreak, when Germany was mired in stalemate despite its use of poison gas and unrestricted submarine warfare, Wilhelm said, “I did not want the war.”

It did not matter. Foreign opinion, high and low, held the kaiser responsible for German militarism and aggression. The first serious call to put him on trial was published as early as October 1914 by an anonymous writer in The Edinburgh Review. By 1918, the idea of a trial was so commonplace that, as the armistice neared, French prime minister Georges Clemenceau commissioned a report from two University of Paris law professors on the Kaiser’s legal responsibility for aggressive war, treaty violations, and breaking the laws of war. The British Cabinet set up a Committee of Enquiry into Breaches of the Laws of War, which similarly included aggressive war and treaty violation.

Five days before the armistice, Attorney General Frederick E. Smith of Britain told the committee, “Our own view is that an aggressive War was forced upon the world by an ambitious and unscrupulous power, and that the challenge so developed involved the whole future of the Public Law of States.” He summarized what he took to be the German view: “Inasmuch as international law has no sanctions which it can apply to the conqueror, it is a matter of the most complete indifference to us whether…we have broken international law or not.” But Germany had not conquered. The Allies had won; they had fought, Smith said, “for the purpose of re-establishing the authority of international law.” The task now was to restore it.

None embraced that challenge more wholeheartedly than Clemenceau and British prime minister David Lloyd George. Both shared the conviction that Kaiser Wilhelm was guilty of launching an aggressive war, breaking the treaties guaranteeing the neutrality of Belgium and Luxembourg, and presiding over military conduct that amounted to “terrorism,” a term referring to actions such as the massacre of almost five thousand civilians in Belgium and northern France, the unlimited exploitation of occupied zones and their inhabitants, unrestricted submarine warfare that targeted neutral shipping and hospital ships, and other operations covered under the excuse of “military necessity.” In their view, all these were international crimes for which the kaiser could and should be held legally responsible. Indeed, Lloyd George was reelected in December 1918 under the popular slogan “Hang the Kaiser.” Italy’s prime minister, Vittorio Emanuele Orlando, was less certain. But the main obstacle proved to be the United States.


William Schabas, the author of The Trial of the Kaiser, is an expert on international criminal law. He shares the view common among international lawyers and international relations theorists that Lloyd George and Clemenceau were mistaken, and that at the time neither aggressive war nor breaking treaties was a crime under international law. They were instead political offenses that had hitherto been handled politically, for example by imposing reparations on the offending nation or taking some of its territory in compensation. If the Allies went ahead and tried the kaiser, they would be applying ex post facto laws. They would also break a long tradition holding that no ruler could be tried before a foreign court. What sort of court should have jurisdiction? The Trial of the Kaiser focuses on how contemporaries tried to solve these legal “riddles.”

The least difficult issue was the immunity of a head of state. Before Woodrow Wilson arrived in Europe for the Paris Peace Conference, Lloyd George, Clemenceau, and Orlando (after some hesitation) had already agreed that Wilhelm must be tried for “being the criminal mainly responsible for the War and the breaches of international law” committed by German forces. The fact that both Britain and France had in previous centuries tried and executed their kings made the step easier for them to take.

US secretary of state Robert Lansing, however, was horrified. Lansing, an international lawyer, chaired the Commission on the Responsibility of the Authors of the War and on Enforcement of Penalties, which was charged with resolving the legal issues and language of the Treaty of Versailles. He argued strongly for the immunity of sovereigns from prosecution in foreign courts.

France’s representative, Ferdinand Larnaude, a professor of public law at the University of Paris and one of the authors of Clemenceau’s report, replied that Lansing had confused the immunity that rulers might enjoy before domestic courts with the obligation that state leaders owed to the international community. Greece’s representative added that trying the kaiser before an international rather than a national court should solve that problem. And besides, if the indictment were included in the Versailles Treaty, Germany’s signature would mean that it had agreed to the trial, thus waiving whatever immunity might still attach to the royal personage. The commission’s final report stated flatly that “there is no reason why rank, however exalted, should in any circumstances protect the holder of it from responsibility…. This extends even to the case of Heads of States.” Article 227 of the Versailles Treaty thus “publicly arraign[ed]” the kaiser and called for an international tribunal to try him.

An international tribunal already existed. The Permanent Court of Arbitration had been established at the 1899 Hague Peace Conference, which had codified the laws of war, but it was not a criminal court, and states submitted their disputes to it only voluntarily. Thus it seemed unsuitable as a venue for a high criminal trial. In March 1916 a French deputy had already suggested establishing an international court for postwar trials. An international criminal court of this magnitude, however, was unprecedented (which is why Lansing opposed it), and it raised many questions. Whose representatives would sit on it? What procedures and rules of evidence would it follow? What sanctions could it apply?

The French report commissioned by Clemenceau had argued that the Allies and Associated Powers (Britain, France, Italy, Japan, and the United States), not the defeated Central Powers or any neutral party, should appoint the judges for two reasons: first, they were the “tacit mandatories” of the small states that German hegemony had threatened to swallow up and that were too weak to defend themselves, and, second, the wartime alliance was the only organized international community that existed until a proper League of Nations could be established. It left the procedure and sanctions to the judgment of the court.

The final version of Article 227 followed these recommendations. In a very interesting section on the actual preparations for the trial, Schabas criticizes the Allies (chiefly Britain and France) for giving so little attention to details concerning the court’s protocol. But in 1945 the International Military Tribunal at Nuremberg proceeded in much the same way: it excluded both neutral and German judges, it set its own procedures and rules of evidence, and it observed its own Charter as the law. Its great advantage was that it was following a path already traversed in 1919 and—a significant difference—it had both the defendants and, more important, the incriminating documents in hand.

Treaty violation was enormously important to statesmen in 1919, yet their concern had less of an impact on future international law on that legal issue than on any other. Schabas’s account does not make clear why. After all, Imperial Germany’s breach of the 1839 treaty guaranteeing Belgian neutrality caused Britain to enter the war. That treaty was signed by all the major powers of Europe, acting as guarantors, and was designed to prevent any one of them from attaining continental hegemony by expanding at the expense of weaker, strategically located states such as Belgium. It was therefore the major diplomatic and legal security instrument of the nineteenth century.


Chancellor Bethmann Hollweg had admitted publicly on August 4, 1914, that Germany’s invasion of Belgium violated treaty law. The British attorney general called the matter “an absolutely clear issue,” and said that if Germany had won the war, “public law and the sanctity of treaties would have disappeared in our day and our generation from the world.” What sort of law could exist, if treaties meant nothing? Even Imperial Germany had contemplated trying Romania’s king for breaking its treaty of alliance with the Central Powers in 1916. The Nuremberg Charter followed the same logic, listing twenty-six treaties violated by Nazi Germany. But international criminal law has not developed along these lines. The Rome Statute (1998) of the International Criminal Court (ICC) does not list treaty violations among the core international crimes.

The most enduring legal dilemma was aggressive war. The ICC did not receive final jurisdiction over that crime until July 2018. The problem was defining “aggression,” a process that stretched from 1947 to 2010, when nations finally agreed that aggression was “the use of armed force by a State against the sovereignty, territorial integrity or political independence of another State, or in any other manner inconsistent with the Charter of the United Nations,” and that persons in political authority could be tried for it.

In stark contrast to the post–World War II era, no one in 1919 was concerned with the definition of aggressive war. Everyone knew it when they saw it, and all, including Wilson, were convinced that Germany had launched one. Moreover, everyone described it as a “crime.” But they disagreed on how to define a crime in international law; that was the heart of the matter, and it is the basic question posed in Schabas’s book. There were essentially three positions.

The first was Lansing’s rigid positivism, based firmly on domestic law. He cited a US Supreme Court opinion of 1812 that for a crime to exist, a legislature had first to make “an act a crime, affix a punishment to it, and declare the court that shall have jurisdiction of the offence.” For Lansing, “what is true of the American States must be true of this looser union which we call the Society of Nations.”

The classic view of criminal law since at least the eighteenth century was “no crime, no penalty, without law” (nullum crimen, nulla poena sine lege). Positivism, the dominant legal doctrine of the nineteenth century, demanded more: “without previously written law.” Because nullum crimen protects the rights of defendants against arbitrary state overreach, it is the fundamental tenet of legality. Nowadays, after decades of codification of international law, its strictures can more easily be met. But in 1919 not even the laws of war contained specific sentences or named courts to handle the offenses listed in the Hague Convention of 1899. It was therefore possible in 1919 for a person acting in an official capacity to violate international law, yet not to have committed a “crime” in the positivist sense endorsed by Lansing. If such a person—say, the kaiser—were put on trial, then he would be tried ex post facto. This was the central American complaint regarding all the legal issues, whether of aggressive war, treaty violation, immunity for heads of state, or the international tribunal: they would all operate “retroactively,” as Wilson complained to Lloyd George.

Fulfilling the nullum crimen standard of legality was extremely difficult for international law in 1919, for only one of its sources (treaties or conventions) was in fact written. The main source, customary international law (CIL), was not; it derived from consistent state practice understood by statesmen and diplomats as obligatory. CIL was very like the common law with its pragmatic, but unwritten, development through time. It was thus easiest for Great Britain, a common law state, to argue the second position: regardless of the lack of written law or an already-existing tribunal, the case was “justiciable by the settled opinion of these fourteen, fifteen or sixteen States which are now engaged at the Peace Conference”; “it is right we should bring to trial those who are responsible for such unconscionable breaches of the principles of humanity,” as Solicitor General Ernest Pollock reasoned. It is remarkable that Britain’s representatives did not make the stronger arguments based on state practice since the Congress of Vienna, which—with the exception of the wars of Italian and German unification, recognized as just under the principle of self-determination—had avoided all Great Power conflicts on the European continent since 1815, and on the strong expectation of international mediation by the Concert of Europe. Perhaps they found their interpretation too obviously true.

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David Lloyd George, Georges Clemenceau, and Woodrow Wilson at the Paris Peace Conference, circa 1919

The French argued the third position. The report commissioned by Clemenceau struck out into new territory. It declared, “A new international law has been born” out of the facts of the war and had been “anticipated in international custom.” It reminded readers of just war theory, “too forgotten today…which did not hesitate to punish most harshly the makers of unjust wars.” It noted that Kaiser Wilhelm had seized every opportunity to brag about his own power, and even quoted some of his more notorious speeches. The report argued that nullum crimen was appropriate for domestic law but must bend for large political crimes, “in order to adapt to the exceptional circumstances of public law.”

Clemenceau, the only nonlawyer among his fellow statesmen at the Council of Four (which also included Wilson, Orlando, and Lloyd George), took the report’s argument to its final conclusion: the Treaty of Versailles should make new law based on the requirements of the international community. “Civilization,” he argued, “is the organization of human responsibilities…. We now have the perfect opportunity to take the principle of responsibility, which is at the basis of national law, and transpose it into international law.” The treaty writers, he said, “will share in the glory of something unprecedented—I readily acknowledge—by establishing international justice,” which until now had “existed only in books. Finally, we will make it a reality.” Orlando embraced Clemenceau’s views “because they raise us above the legal technicalities. It is history that is taking place. It is no longer law. If we consult the codes, we will have great difficulty in finding there what we seek.”

Nevertheless, the United States stood firm. The pattern was always the same: Britain, France, and other powers argued for criminal trials; the United States refused; the other powers weakened (often for practical, not legal reasons) and finally gave in. Wilson arranged a “compromise” that produced the odd wording of Article 227, which “publicly arraign[ed] William II of Hohenzollern, formerly German Emperor, for a supreme offence against international morality and the sanctity of treaties”—morality, not law. The Allied reply to Germany’s law-laden rejoinder, which found Article 227 devoid of “any legal basis,” denied that the treaty had a “juridical character as regards its substance, but only [did so] in its form.” That is, the treaty had poured politics into legal form.

Even so, the Netherlands, where the Kaiser had fled after Germany’s collapse in November 1918, rejected Allied requests for his extradition on the ground that Article 227 violated the rule against retroactive punishment. A quixotic attempt by several rogue US officers to kidnap him netted only a stolen ashtray embossed with the royal coat of arms “adorned with a pipe-smoking dog that bore the monogram ‘W.I.,’ presumably meaning ‘Wilhelm Imperator.’” No international trial of the kaiser was ever held.

Schabas has done meticulous research among the unpublished archival records of this titanic legal struggle. Unfortunately he does not reference the historiographical literature, so readers will not learn from his book how historians have interpreted the negotiations and effects of the Versailles Treaty. He is also agnostic about the facts (did Germany wage an aggressive war?) and seemingly even about whether aggressive war violated international law (even if it was not a “crime” in the domestic sense).*

Nevertheless, Schabas agrees with much recent historiography that has positively reevaluated the enduring importance of Versailles, despite its immediate failure to prosecute public officials. He writes that “with the exception of the Charter of the United Nations, the Treaty of Versailles…was the most important international convention of the twentieth century.” The treaty gave legal recognition to the new state borders of Europe, and it set down broad rules governing international state conduct, both in the reasons it gave for its treatment of the defeated Central Powers and in the Covenant of the League of Nations.

Its painstakingly documented list of thirty-two separate war crimes constituted “one of the most enduring contributions…to the development of the laws and customs of war.” It specified crimes against civilians (ranging from murder and torture to rape, deportation, and forced labor), against prisoners of war and wounded soldiers, and against civilian and cultural property, and it criminalized methods of combat such as poison gas, exploding bullets, giving no quarter, collective fines, sinking merchant and passenger ships without warning, and destruction of hospitals and hospital ships. An ICC judge has credited the treaty with taking “the first step towards the development of a customary international law norm that rejects…immunity” for state officials.

Schabas notes of the Council of Four that “never before, or after, have the leaders of the world’s most powerful nations devoted so much time to a debate about criminal law and individual responsibility.” He chides them, rightly, for their “amateurishness” regarding important legal questions. But although three of them were lawyers, all were first and foremost political leaders trying, in Wilson’s words, “to create the principle and the penalty” that would safeguard a new world order based on law. To get there, they had to take a leap out of positivism—a leap that Wilson, for all his idealism, refused to venture. The kaiser remained safe in Huis Doorn, the mansion he purchased near the Dutch city of Utrecht, until his death in 1941, when the sequel to World War I was preparing the way for another American, Justice Robert H. Jackson, the chief prosecutor for the US at Nuremberg, to take that leap.