Today war is not only rare, but also illegal and condemned.

Things have not always been that way. The Bible gives an idea about what was seen as just in ancient times. When Moses heard about the campaign of vengeance on the Midianites, he berated his officers for allowing women and children to live (all men had already been massacred). When King Saul merely imprisoned the last of the Amalekites instead of killing them, Prophet Samuel had to finish the job by hacking the chained prisoners to pieces. Saul’s heinous crime even caused God to announce that He had made a mistake in appointing Saul as king. As Hathaway and Shapiro put it: “In the Hebrew Bible, it was often a war crime not to kill civilians.”

Accepting the mass murder of civilians is not just a feature of biblical times, but a feature of international law until the mid-1700s. For instance, Couhnt Pappenheim, after sacking the city of Magdeburg in 1631, let his soldiers run loose through the city, killing, pillaging, and stealing as they saw fit. He described the sacking in a message to the Holy Roman Emperor: “I believe that over twenty thousand souls were lost … All our soldiers became rich. God with us.”

Something has definitely happened in the past few centuries. Many explanations have been offered. War has become more expensive, trade has become cheaper, and economic growth means that prosperity is not a zero-sum game. Nuclear weapons have prevented war. Countries have become more democratic over time. Perhaps the cause is the gradual advancement of morality.

The Internationalists does not dismiss the importance of these factors, but makes a case for the importance of another: the legal status of war has changed, and that these changes have marked shifts in the international order. Hathaway and Shapiro identify two key events: Hugo Grotius’s construction of a legal basis for war in 1625, and the Peace Pact’s (AKA the Kellogg-Briand pact) outlawing of war in 1928.

The Old World Order

Hathaway and Shapiro refer to the legal framework of the international order from 1625 to 1928 as the Old World Order. Its rules were laid out by Grotius in De Jure Belli ac Pacis (On the Law of War and Peace), who began writing it as an effort to justify the capture of a Portuguese frigate by Dutch ships near Singapore in order to avoid legal troubles for the VOC (Dutch East India Company). This is not quite the most virtuous of motives, and it shows.

The essence of Grotius’s argument is the principle that might makes right. Since there is no arbiter for disputes between nations, nations have the right to defend their interests with war, and neutral nations, who do not have the authority to judge which nation’s claims are right, should simply accept the outcome of the war as right. Even if a nation had an unjust cause to fight a war, the nation, its leadership, and military must not be prosecuted or in any way punished for it; they have the right to take their claims to the ultimate court (war).

In some ways, Grotius was ahead of his time. He recognized poison, rape, and “treacherous” assassination as war crimes, and argued that soldiers who committed these crimes could be tried and punished for them. However, Grotius explicitly stated that torture, enslavement, pillaging, execution of prisoners of war, and the killing of unarmed civilians could not be prosecuted. Grotius did consider the needless slaughter of civilians to be unjust, but in his view it was not a criminal offence.

Grotius was also against “hygienic” wars, in which the principal aim is to cleanse a land of a particular group, often for religious reasons. In this way, even the Old World Order was a step above the biblical extermination campaigns and holy crusades of previous centuries.

Follow the rules

One of the most striking aspects of the Old World Order is how deeply and strictly nations adhered to it.

Under the Old World Order, war truly was, as Clausewitz said, “the continuation of politics by other means.” Slaughter and killing were just another part of a complex, formalized system of rules and procedures for settling differences between nations.

To justify wars, war manifestos were written, often commissioned by the state from esteemed intellectuals (for example, Gottfried Wilhelm Leibniz was recruited to write a defense of the Holy Roman Empire’s participation in the War of the Spanish Succession).

War manifestos and complex traditions for declaring war go back far before Grotius. Consider the (frankly hilarious) Roman practice:

During the Roman Republic, a priest would approach the border of any territory Rome intended to attack wearing a wool veil. Once there, he would announce a legal grievance, called the clarigatio. If the other side ignored the clarigatio for thirty-three days, the Senate could authorize war. War would officially commence when the priest returned to the border and, in the presence of three military-age men, threw an iron-tipped spear over the line. As their empire expanded overseas, Rome had to alter the process, for no priest could fling his spear over the ocean. In the revamped system, a priest would take a prisoner from the soon-to-be enemy’s territory and force him to buy a small plot of land on the Campus Martius, the field of Mars, just outside the ancient city walls of Rome. When the prisoner proved unable to meet the priest’s demands, the priest could then throw the spear into “foreign soil,” thereby starting the war, and still be home for supper.

However, the Old World Order differed from past times in standardizing the rules across all “civilized” (i.e. European) countries, and making sure that these rules were followed with a rigor and consistency that would make many modern international institutions envious. The Internationalists offers countless vivid examples, of which a few are summarized below.

Napoleon’s wars killed 7 million people over 11 years across Europe. He was vilified by the press of Britain and many other countries, and thought of by much of Europe as the physical manifestation of evil.

Yet after his defeat in 1813, the Allies made no attempt to execute or imprison him. By the rules of the Old World Order, as the leader of a country he had the right to wage war, and therefore could not be put on trial since he had done nothing wrong. He retained the title and role of Emperor (albeit of Elba, not France), where he lived in comfort until escaping to France and starting another war.

When he lost yet again in 1815, he surrendered to the English, who once again were unable to prosecute and punish him because of legal difficulties. This was not due to lack of trying. One solution was to treat him as a pirate (a criminal offense) because he had escaped Elba on a ship. However, the British Parliament had recognized the conflict as a war, which foreign nations had the right to wage, and so this idea had to be dropped. Ultimately the British Parliament had to pass a special law to justify detaining Napoleon on St. Helena.

In 1891, a Sioux Native American called Plenty Horses shot, without provocation, a US lieutenant delivering a message. He was tried in court, and acquitted after it was established that there was a state of war between the Sioux and the US. War was not just a justification for murder, it was a strong enough justification that the courts of a country acquitted murderers of its own citizens on that basis (though conveniently enough, the ruling that there was a state of war between the Sioux and US also justified a mass murder committed earlier by US forces).

The Old World Order also stated that neutral countries have to treat belligerents in a war equally, a stark change from classical Greece and Rome (ancient Greek and Latin do not even have a word for neutrality). This, too, tended to be followed to the letter.

Old World Disorder

Significant changes to Grotius’s model began to appear only a century after his seminal work.

By the mid-1700s, a distinction started being made between civilians and soldiers, and the slaughter of the former was increasingly frowned upon. The international lawyer Emer de Vattel even declared: “[civilians have] nothing to fear from the sword of the enemy” (I assume the civilians themselves were not polled).

In the 1800s and early 1900s, war was further regulated by international treaties against killing the wounded, fragmenting small arms ammunition, and the execution of surrendered prisoners of war.

Why? Enlightenment ideals and a growing appreciation of the value of life were certainly a part of it. Other possible reasons that Hathaway and Shapiro cite are the influence of chivalrous aristocrats who considered wars to be formal duels between nations, as well as the horror of long wars in the 1600s and 1700s.

Whatever the reason, by the late 1800s the trend was towards war being made ever more humane by regulations. There is a limit to how humane war can be made, however, and so the natural next step was to ask whether war itself should be outlawed.

The New World Order

World War I was the culmination of the Old World Order. It was a colossal waste of human life and potential, triggered by nations sleepwalking into war to defend against perceived wrongs. It was fought in precise accordance with Grotian rules: nations had issues with each other, and took them up “by other means” once normal politics had failed.

World War I set in motion various plans and movements to prevent another world war. The solution of the League of Nations was to prevent war by threatening war on those who waged war (though it still allowed nations to go to war after three months if they were unsatisfied with the verdict of the League’s tribunal). This was, to put it mildly, somewhat self-defeating. Hathaway and Shapiro do not mince words: “The League of Nations did not herald the end of the Old World Order. The League was its reprieve.”

The book details the story of how several people, most importantly James T. Shotwell and Salmon O. Levinson, gradually built momentum for the outlawry of war movement in the 1920s, leading to the signing of the Peace Pact in 1928 by fifteen nations. Kellogg, the US secretary of state, took much of the credit, and an undivided Nobel prize, for the achievement. This was mostly thanks to his attempts to discredit Levinson: to the Norwegian ambassador who had much influence in the Nobel Committee, he wrote, among other more direct attacks: “… a man by the name of Levinson in Chicago - I have forgotten his first name - … claims to be the originator of the idea”.

(This is not the only instance of dubious credit being given in the field international law: Grotius has often been honored for his contributions to peace, and, is, ironically, the patron saint of the building that houses the International Court of Justice.)

The Peace Pact, as we all know, succeeded perfectly, and never again was a war fought on Earth.

Happily ever after … ?

Not three years after the signing of the Peace Pact, Japan invaded Manchuria. Japan, a quickly modernizing power, had had a rather sudden introduction to the Old World Order in 1852 when four US ships arrived on its coastline and engaged in classic gunboat diplomacy to get the country to open its trade. Just as the country had begun exploiting the Old World Order to its own benefit, the world order had changed.

The League succeeded in not recognizing Manchukuo (Japan’s puppet state in Manchuria) as a state. However, it is telling that the League’s greatest success in the situation was to not do something. Many countries, foremost the US, resisted imposing sanctions because of concerns about profitability and lingering Old World Order beliefs about mandated neutrality.

Some sanctions were, however, imposed on Italy following its annexation of Ethiopia, but nations were not willing to set up sanctions strong enough to be effective. The use of sanctions against a warring nation was a revolution; under the Old World Order, it would have violated the duty of neutral nations to treat the aggressors equally.

Thus the 1930s were marked by nations being caught halfway between the Old and New World Order, unable to effectively use enforcement methods from either. At the same time, other nations, most prominently ascendant industrial powers like Germany and Japan, began to increasingly shun the New World Order of non-violent conflict resolution, partly out of a (not entirely unjustified) belief that it was an attempt to lock the world’s borders in place to the benefit the ruling colonial powers.

If World War I was the culmination of the Old World Order, World War II was the battle of the Old against the New. The Axis powers acted according to the older model - the principle that might makes right - and thus sought to increase their power through conquest. The genocide perpetrated by the Nazis drew upon an even older basis for war: the concept of hygienic war, waged for the purpose of ethnic cleansing.

On the other hand, the Allies belied, to varying extent, that this is not a valid basis for international law. Of course, any side in a war, particularly the ones who write history afterwards, tends to believe they were motivated by some higher purpose. But the end of the war shows that the idealism of the Allies was genuine. Surviving Nazi leaders were given a trial at Nuremberg, in accordance with the principal that they had committed a crime. The book gives an excellent overview of the trials and the key legal figures on both sides: Carl Schmitt (a Nazi), and Hersch Lauterpacht (a Jew).

The end of World War II also saw the formation of the United Nations and other international organizations. The rise of supranational organizations ameliorated the lack of arbiters for international disputes that had formed the bedrock of the Grotian model. (It was not without hitches, though: negotiations for the formation of the UN almost stalled when Stalin demanded separate votes for all 16 Soviet republics. In the end, he settled for instituting the veto system.)

Finally, in an act that would have made most of their predecessors for the past four hundred years turn in their graves like propellers, Allied leaders largely refrained from dividing the spoils and claiming territory for themselves. Germany was split into East and West, but otherwise borders largely reverted back to an earlier date.

Law & order & changing values

Which earlier date? 1928. This is the basis for the authors’ claim that the Peace Pact was a seminal event; though it did not quite end war, it marks the date before which most conquests were recognized, and after which most conquests were not recognized and later reversed.

This is illustrated in the following graph of conquered territory (the units on the y-axis are millions of square kilometers):

IMAGE

(The spike in the late 1800s is partly due to colonial powers claiming big chunks of Africa.)

In charting the story of the outlawry of war, The Internationalists argues for the importance of the 1928 Peace Pact. While it provided a legal basis for post-war reversions of territorial changes and for the Nuremberg trials, it is still a legal document. Thus, half the question of why war has declined remains unanswered: yes, it was made illegal, but laws, especially toothless international treaties, tend to be reactions to changes in values rather than causes of it.

Somehow, Levinson and Shotwell managed to create enough momentum to outlaw the most fundamental part of international law for the past three centuries. They did not achieve this in a vacuum. World War I certainly played a major role in forcing a reconsideration of war. The transition from brutal hygienic conflicts to a more codified form of mass slaughter to an increasingly regulated form of massacre, and finally to the complete outlawing of armed conflict, indicates that some sort of background pattern of accumulating humanism must also be at play. In the post- World War II era, the economic benefits of trade are another factor. But what are the relative importances of these factors? Are the factors keeping the world at peace different from the ones that inspired the Peace Pact in the aftermath of World War I? The Internationalists is ultimately legal history - though a surprisingly fascinating legal history - and so these questions remain outside its scope.

Peace, what is it good for?

Whatever the reasons for the decline of war, the decline has been massive. As Shapiro’s and Hathaway’s statistical analysis points out, before 1928, an area of territory equal to eleven Crimeas was seized by conquest every year (almost one per month), though admittedly the seizing of massive parts of Africa in the late 1800s pulls up the average. The average state before 1928 was invaded once in a lifetime; today, the average is once in a millennium. And, of course, conflict deaths have also fallen massively.

The outlawry of war has, however, had one major side-effect. Whereas frequent wars previously pruned the ranks of nations (in fact, modern nations emerged mainly to fight these frequent wars), in today’s world strong nations do not invade the weak and therefore failed nations can continue to exist. Thus one main category of armed conflict in the modern world: civil wars and violence in failed states (and, of course, terrorist activity operated out of these states, but the resultant deaths are massively outnumbered by deaths within the states themselves).

The second category is cases where there is legal dispute over ownership. Since 1928, states cannot gain territory by occupying it with troops; the only way to get land is to get the rights to it. If the legal status of a territory was unclear in 1928, and the claimants have not reached a diplomatic solution, it largely remains unclear today. Most cases are the result of vague or even contradictory agreements by retreating colonial powers (like Palestine) or uninhabited islands no one bothered to claim, (like those in the South China Sea - or is it the West Philippine Sea?).

In the latter case, Shapiro and Hathaway note that part of the reason why the islands are so contested is not because international law has failed, but precisely because it has succeeded so well: the main perk in owning the islands is the 430 000 square kilometer (370 km radius) exclusive economic zone that is granted by the UN to owners of coastal territory, which is only valid if recognized by the international community.

Whatever the failures of international law and organizations in keeping peace, they are massively outweighed by the benefits. On any conceivable metric, the post- World War II era is more peaceful than any before.

The book ends with a plea for upholding the vision of the “Internationalists” who organized the outlawing of war. The real danger is not that the New World Order fails, but that the world forgets how much it has achieved.