Humane: How the United States Abandoned Peace and Reinvented War

by Samuel Moyn

Outright pacifists remained inveterate in their cause but were dwarfed by those willing to minimize the chance of war at the price of compromise with states. In old and new media—with the bestselling compilation of photographs The Horror of It (1932) reminding audiences of World War I’s depredations, Hollywood making a movie of Remarque’s novel within a year, and World Peaceways taking to the radio waves—peace propaganda washed over the public. It was an extraordinary mobilization never to be repeated, except in the Vietnam years. The

After the massacres of World War I, however, humane war lost its relative importance as once-radical hopes for peace became mainstream themselves. “The fundamental problem of our time,” intoned one who explained that pacifism had become the very purpose of his field, “is to civilize and demilitarize the state, so that men can become free, and true masters of their destiny.”

“Many people will approve of a decision rationalized in legal terminology simply because it represents that holy symbol, the law,” Wright insisted. For that very reason, part of the internationalist’s agenda was to canonize a new and superior arrangement of power in the world in a legal scheme, one shaped by enlightened public opinion, and shaping it.

One reform plan quick to take shape during World War I was to hold legally accountable despots and madmen who disturbed the peace.

Already in 1918, calls were rife to try the German Kaiser for initiating the conflict—but not for the numerous war crimes of his forces in the field, starting with their atrocities in Belgium on the way to the trenches. One of Wright’s first publications explained how it ought to be plausible under international law to hold Wilhelm II accountable for his ...

Most of the early public uses of the phrase “crimes against humanity,” now associated with grave atrocities during war, allocated responsibility for war itself. They came from the British prime minister David Lloyd George and other entente politicians who intended to target the German leader (if not because war itself was illegal, then because of his violation of Belgian neutrality, guaranteed by treaty). As the war cl...

Similar cries of the Canadian prime minister and Italian president for postwar justice indicates how popular it was in 1918–19 to call war itself, rather than its attendant cruelties, a “crime against humanity.” (The Kaiser fled to the Netherlands, which refused to extradite the queen’s “Uncle Willy.”)

As this rhetoric indicated, the war on war that peace advocates had initiated now became the premier goal of international affairs. More constructive were new institutions that would preserve the peace to which World War I finally led. The very first of the preambular purposes of the League of Nations Covenant worked out at the Versailles Peace Conference in 1919 marked “the acceptance of obligations not to resort to war.” This first bid at international organization bound signatories “to respect and preserve as against external aggression the territorial integrity and existing political independence” of member states.

And famously, the United States remained outside the League after the Senate failed to approve the Versailles treaty. For the Americans and others who supported binding legal arbitration and the pacific settlement of disputes, the war ended with their dreams not realized but smashed. Even within the League, the primary solution was to give each nation its own power to keep the peace rather than transfer authority or power to any international organization to do so. Nine new “nation-states” were created in Eastern Europe where three now-defunct empires had once ruled, with the hopeful assumption that contention would be replaced by harmony. But advocates of systemic peace were not giving up.

Another popular idea was disarming states. If they retained carte blanche to conduct war, reducing their weaponry would at least make the consequences less cataclysmic.

Instead, disarmament would place limits on otherwise legal weapons, or even reduce them, a proposal that was especially attractive to states that could not or did not want to spend on arms races—not least frightening naval buildups.

Wright was a fan of international arbitration, and he would spend the rest of his career looking for a functional equivalent to it. Before the frost of the late 1930s overtook them, however, various flowers had sprouted from its grave. Outside the League, in an instrument negotiated among Europeans at the Swiss lake town of Locarno in 1925, Germany’s border with its western neighbors was set, with Britain promising to guarantee it against alteration or incursion by either side. The agreement was the high point of optimism for European peace. It left much undone, including arms reduction and the status of Germany’s eastern borders. And even at this bright moment, the continuation of the sorts of alliance blocs that had brought about World War I threatened disputes, and so were a bad omen of a darker future.

Most significant, leading powers replaced arbitration with a system of collective security under international law that allowed for identifying aggressors and policing them for the sake of peace—what the United Nations does, in theory, to this very day.

It resurrected a binding scheme for peace among states from its grave but made it political rather than judicial. It worked by proposing to federate states in a League powerful enough to deal with rowdy members when they arose. A jury of the states themselves, rather than independent judges, would pass a verdict on warmongers and stop them.

Not only would this outlawry plan require the United States to step up, but also it would demand the abandonment of the idea that a state could be neutral toward aggression elsewhere. Either the world got together to keep the peace, combining forces against aggressive states that interrupted it, or war would continue forever.

The rules themselves would have to allow for self-defense, as in domestic criminal law. But once again that very analogy showed that preventing war was possible. It was just a matter of deciding what could count under law, what would not, who would decide, and who could become the globe’s constable.

The hard part would be to get states—starting with Wright’s—to agree to a system of policing to check aggressors.

The most famed of the peacemongers’ efforts was the Kellogg-Briand Pact of 1928. Named after Frank Kellogg and Aristide Briand, respectively the American secretary of state and the French prime minister who proposed it, the treaty was negotiated quickly, in the mid-1920s era of good feeling on the European scene following Locarno.

But there was no enforcement provision: the treaty contemplated the pacific resolution of disputes, though to do so was like saying eating too much food is illegal, then gesturing to the fact that people will need to figure out how to stick to their diets.

one astute observer insisted, the Kellogg-Briand Pact “does not outlaw war but approves it,” for anyone who had eyes to see, for states conditioned their acceptance of the treaty on exceptions, far beyond the claim to self-defense that still permits force today.

Wright and others who saw beyond the hype understood that the treaty’s true meaning was not the immediate victory of peace. Instead, it anticipated the paramount responsibility of the United States in advancing that cause. “The historical significance of this treaty, if it can still be said ever to have possessed any,” one wise observer of the situation remarked, “resided exclusively in the association of the United States in the campaign for the maintenance of peace.”

Capitalizing on its victory at The Hague a generation before, the United States insisted that nothing done pursuant to the Monroe Doctrine could in principle qualify as a violation. Kellogg told the Senate that the treaty did not forbid self-defense, whi...

In response to the United States conditioning its signature on its birthright of hemispheric intervention, Argentina, Bolivia, Brazil...

Now Chamberlain reserved his nation’s right not simply to defend itself but also to deploy armed force in “self-defense” wherever the British Empire’s interests were at stake—which is to say, anywhere.

How did the solemn renunciation of war succeed in garnering the assent of the United States—including the notoriously skittish Senate—where arbitration had failed? The success was due principally to the fact that the Kellogg-Briand Pact left open the room for maneuver that advocates of a compulsory form of arbitration were trying to close. By the 1920s, Americans who had refused to join the League itself were willing to join in hallowing European peace rhetorically.

Wright knew the hard part was going to be inciting Americans to interpret the commitment they had now made in his way rather than Borah’s. When an aggressor rose anywhere, Wright wrote, it violated the rights of the United States under treaty no matter what the country chose to do about it. No uninvolved bystander anymore, America was an injured party. “Wars of aggression,” Wright explained in 1930, “are no longer moral offenses against the victim alone, but legal offenses against every state party to these multilateral treaties.”

This was no merely hypothetical question, for Hitler rose to power in Germany three years later. Even before, Wright had cause for encouragement when the Republican Henry Stimson, a Wall Street lawyer and Herbert Hoover’s secretary of state, responded to Japanese “aggression” in invading Manchuria in 1931 by saying the United States would not recognize this brazen act of colonialism as lawful.

International law had once “converted violence into legality, robbery into title, might into right.” The idea that it would consecrate peace instead was not new in content but had suddenly moved from books into practice. Of course, this didn’t solve the real problem. Somebody would have to boot Japan out rather than deem its annexation illegal alone. That the United States now withheld recognition from the fruits of someone else’s war hardly meant it was committing to keep the peace.

The question remained: Would the United States step up to guarantee eternal peace after its missed opportunity when World War I ended? Already the greatest world power, would it not have to accept the risk (however hypothetical and unlikely) of seeing its own wars condemned as illegal? Either way, wouldn’t the United States also have to help put down any newly recognized aggression—or even lead the way in doing so?

Wright replied that the world had changed, as ultimate American entry in World War I already proved. Why not arrest the coming of faraway unwanted conflict early rather than get swept in again? “If it is practically certain that we will become involved in any war between great powers which lasts for a considerable length of time, whatever we do,” he observed in 1935, “then a policy of co-operation to prevent war could add little to the risk.”

Now the next terrible blow to that dream—World War II—was on the way. Had Suttner lived in vain? Had Wright wasted his time? War remained endemic, or even worsening, its brutality increasing along with its frequency. It was hard to take seriously Tolstoy’s warning that making warfare humane could postpone peace—yet.

Advocates of peace like Suttner worried from time to time that humanizing warfare would rule out its elimination. And the sniping back and forth between proponents of the two goals was far more open and vivid before World War II than in any era since. The truth was, though, that the peace movement need not have worried, since for all its failures the cause of making war more humane was faring worse. Humane war did not get off the ground, so it could not yet threaten peace.

Far more gallingly, the protections did not even apply to the most atrocious forms of combat—colonial and counterinsurgent warfare, especially against racialized foes. And in World War I and long after, what rules did apply were almost universally ignored.

In this new era, civilian resistance confronted occupying armies but also ruling governments everywhere. States feared that struggles on foreign territory could make their occupations complicated. They also increasingly worried that their own citizens might rise up and make revolution. In response, the 1874 Brussels Declaration on the customs of war set out on a very different trajectory than the Geneva Convention ten years before. The Swiss plan for humanity in warfare would remain marginal for a century.

The results strove to give states maximum control over potential chaos, licensing harsh occupations so that they would not devolve into partisan wars. The point was to protect soldiers from enemy civilians, not the other way around. As for internal wars like the suppression of the Commune, international laws of war were not relevant by design.

He was fooling himself: international law cajoled states only so far and no farther.

Regular violence was the font of virtue for males, without which humanity would “sink into materialism.”

The Hague treaties of 1899 and 1907 on rules for fighting were in some places more than cosmetic. “At least,” Fried observed, “no one can now say that no rules apply to war.” However paltry, it was a real victory. The original Geneva Convention’s protection for the wounded in battle was now extended from armies on the ground to sailors at sea. Disfavored practices such as denial of quarter and killing prisoners of war—Prince Andrei’s proposal—were absolutely prohibited. There was even some early civilian protection (again, with emphasis on property), especially in situations of military occupation. As they had at Brussels, delegates also affirmed in the treaty that there was some limitation to the means armies could use to win, leaving it vague what they were ruling out.

They did get specific when it came to weaponry. Soft-tipped bullets that caused grievous injury by expanding in flight were banned.

In the successor conference in 1907, the most novel development was the agreement to proclaim the illegality of means of war that inflicted “unnecessary suffering”—once again, without defining what counted.

But the lion’s share of the new Hague rules in 1899 and 1907 had nothing to do with humane war. Instead, they codified military customs and definitions of military necessity. Provisions for occupation gave enough wiggle room for armies facing civil disorder to crack down. For those in the know, Dunant’s Geneva Convention was beginning to look more and more like the rare occasion when the interests of militaries and the goal of reducing suffering coincided.

Tolstoy had worried about the compromises advocates would make to work with militaries, the same way prior do-gooders had compromised with slaveholders not to abolish slavery but to make it more humane. For a long time, there was no space for compromise, and instead plenty of humanitarians were fooled into giving away the store to militaries. As a result, there was no humane war in sight. The Geneva Convention aiding wounded soldiers had already involved a strateg...

Though Dunant had been interested in proposals to set up international arbitration as an alternative to war for some time, her browbeating drove him to openly embrace the goal of peace.

Dunant pretended retroactively that his call for humane war had been issued to “instill” in people “a sacred horror of war in order to make them into friends of peace.” With enough to go on, Suttner advertised to any takers his assurance that he did not want to be remembered as an advocate of endless if humane war if there was a chance of peace.

But the situation was worse than it seemed. It wasn’t just that the effort to make war more humane failed on its own terms. It was that most laws of war didn’t apply or were ignored when it came to counterinsurgent and colonial war. Advocates of humane war concentrated on the dreadful clash of great powers clustered around the Atlantic Ocean. Like the organized peace movement, the exponents of humanity spoke for white and increasingly wealthy populations outraged that war brought so much ruin to modern societies boasting the greatest accumulation of power and riches ever seen. Few proposed that ending war or making it more humane pertained to the globalization of the European empire, already centuries old, that continued into the twentieth century—or that they applied to American overseas expansion in the same years.

The peace movement itself was always the affair of white men and women, not only in terms of who participated but also in terms of who was supposed to benefit.

The “murder of men by men” that peace advocates such as Carnegie wanted to stop did not rule out bloodcurdling atrocities beyond the European and transatlantic space. Those few voices who might have demanded a global peace transcending human difference would have been abandoned by comrades who thought that a white peace established by force in a world of racial hierarchy was the entire point.

Yet the regulation of how war was fought remained even more profoundly racialized. Colonial war was forced into a nether zone of asymmetrical if sometimes conventional conflict, counterinsurgent suppression to restore order, and imperial provisions licensing emergency measures and martial law. In all these versions of global fighting, rules were even less significant a constraint than on the transatlantic scene. One reason humanitarians and peace advocates alike gained more traction when it came to great-power conflict across borders was that few people found anything wrong with counterinsurgency—the suppression of the irregular forces of enemies—within empires. It was hardly by accident that international law regulated war between states, not within colonies. As a result, the “progress” that the campaign for humane war embodied did not interfere with the global designs of states.

As a result, militaries developed—most famously in the British colonel C. E. Callwell’s manual for small wars—counterinsurgency theory for global violence that they would apply into the twentieth century.

The laws of a scientific age did not prohibit asymmetry and still do not. Only occasionally more ticklish was the fact that whenever Europeans treated non-Europeans differently while fighting counterinsurgent wars, they blew past limits whether old or new. Most notably, they declared war on whole populations.