The Treaty to Outlaw War
How a group of diplomats tried to ban war — and failed.
Benjamin Franklin once remarked “There never was a good war or a bad peace” and in the aftermath of the First World War, his opinion resonated with many. After four years of blood-soaked combat, which saw as many as 20 million killed and the great empires of Europe reduced to ruin, it was clear that the world would emerge from the Great War irrevocably changed.
The impetus for change would be heavily influenced by progressives in the United States, who, appalled at the destruction of 1914–1918 and keen to avoid a return to the imperial rivalries that had led the world into war, pushed heavily for a new global order of international politics. This new progressive order looked to build a world based on international cooperation, with the great powers of Europe and Asia co-existing as peaceful economic competitors.
It was in this spirit of progressive optimism that the Kellogg-Briand Pact (1928) — a treaty to outlaw war as a tool of national policy — was devised. But despite its lofty aim of preventing warfare through international law, the policy, and progressive idealism more generally, would come crashing down at the first hurdle. It is to the context and challenges of the treaty that we must first turn.
The age of treaties
To understand how the belligerent nations of 1914–1918 arrived at a treaty to outlaw war, we must track the history of international politics in the 1920s — and in particular, the growing role the US was beginning to play in international affairs.
During the First World War, the great champion of progressive politics in the international scene was President Woodrow Wilson (D-New Jersey). His justification for joining the conflict, despite campaigning in the 1916 Presidential Election to keep the US out of the war, was ostensibly to make the world safe for democracy.
Wilson viewed the war as a conflict between liberalism and authoritarianism, and felt it was the duty of the US to tip the scales in favor of democracy. This perspective is apparent in Wilson’s Fourteen Points, laid out in January 1918, which had three key themes:
1. The promotion of democracy in Europe.
2. Encouraging free trade globally (as Wilson believed economic connectivity would deter aggression).
3. Securing the right of self-determination for all nations.
These themes played a prominent role in the post-war settlement, with the Treaty of Versailles (1919) and the League of Nations (1920) bearing the mark of Wilson’s progressive views. However, the progressive and interventionist foreign policy promoted by Wilson continued beyond the immediate end of the Great War — and after his time in office had come to an end.
The Washington Conference (1921–1922) was the next element of the progressive strategy to prevent another war. Concerned about increased international militarism — particularly in Asia — Wilson’s 1916 Republican opponent, Charles Evans Hughes (R-New York), the US Secretary of State in the newly elected Warren G. Harding (R-Ohio) administration, invited a host of nations to Washington. Hughes’ objective was to entice the attending nations to agree to a policy of naval disarmament, and the ensuing Five-Power Treaty (1922) was the fruit of his labors.
The treaty was signed by the US, Britain, Japan, France and Italy, and limited the warship tonnage of the participating nations along the following proportional lines: US (500,000 tons), Britain (500,000 tons), Japan (300,000 tons), France (175,000 tons) and Italy (175,000 tons). It also encouraged the five signatories to reduce the size of their navies by scrapping older vessels, with Hughes aiming to prevent a growing naval arms race and curtail possible tensions between the five nations.
The treaty allocated the US and Britain increased tonnage due to their need to keep both an Atlantic and Pacific navy, and it ultimately resulted in the US scrapping 26 warships, Britain 24 warships and Japan 16 warships that had either already been built or were under construction. The agreement to limit the naval arms race built upon the earlier Four-Power Treaty (1921), in which the US, Britain, France and Japan all agreed to consult one another on any issues in the Pacific. A further Nine-Power Treaty rounded off the conference, with signatories agreeing to respect Chinese territorial integrity.
The Lesson of the Washington Conference is one of growing American influence on the international scene — and especially the progressive strand of American politics. It represents a further attempt by progressives in the US to use America’s position in the interwar years to push for the avoidance of war and diffuse any international flash points using international law.
During this period, the US would play an active role in directing global affairs, despite President Warren Harding (1921–1923) campaigning on a promise to ‘return to normalcy,’ which broadly speaking meant an end to wartime restrictions and a return to peacetime conditions domestically. A follow-up conference in London (1930) would look to build on the agreements and continue the diplomatic path of arms limitation.
The treaty to outlaw war
The progressive appetite to shape the post-World War One geopolitical scene took a more ambitious turn later in the decade, with American progressives attempting to use international law to completely outlaw the use of war by global and regional powers. Whereas the Washington Naval Treaty (Five Power Treaty) aimed to disarm nations and prevent an arms race, the Kellogg-Briand Pact (1928) looked to go one step further and prevent all wars of aggression.
The treaty began as a proposal by the French Minister of Foreign Affairs, Aristide Briand, with the backing of American peace advocates. Briand was worried about the threat France faced from Germany once it rose back to great power status. Fearing a repeat of the First World War — a German invasion and a protracted bloody conflict on French soil — Briand proposed a bilateral peace agreement between France and the US.
Enthusiasm for a French-US agreement was not matched by the Americans. President Calvin Coolidge (R-Massachusetts) and his Secretary of State Frank B. Kellogg both feared that such a treaty would commit the US to war if France was ever invaded or threatened, and instead Kellogg proposed an alternative: an invitation for all nations to commit to outlawing war.
At first glance, a treaty to outlaw war as an instrument of state policy seems incredibly utopian. However, the move had a great deal of public support. After the mass bloodletting of World War One and first-hand experience of total war, both the American and European public were keen to avoid another catastrophe.
The proposed treaty had two key clauses: the banning of war as a tool of state policy and a commitment by signatories to settle any disputes peacefully. Crucially, it would declare only acts of aggression as illegal, with only wars waged in self-defenses permitted. On 27 August 1928, the pact was signed by fifteen nations, including the US, France, Britain, Germany, Italy, Czechoslovakia, Poland and Japan, and over time 47 nations would also add their names to the list of signatories.
The US Senate ratified the pact by 85–1, showcasing the strong level of public support the treaty had among the American people — although the US did reserve the right not to intervene against any signatory nation who failed to uphold their commitment to avoid war.
From peace to war
The Kellogg-Briand Pact had successfully brought both great and regional powers alike from across the globe into an antiwar treaty, but its lofty ambition would quickly unravel after only a few years.
The economic insecurity caused by the Great Depression would set international tensions rising, with nations quickly throwing up tariffs against one another in a last-ditch attempt to protect their own domestic industries. It was against this backdrop that the first major test of the Kellogg-Briand Pact would arise — the Mukden Incident.
In 1931, a section of railway track near the city of Mukden, China, was attacked using explosives. The railway line was owned by the Imperial Japanese Army, and they immediately blamed the incident on Chinese nationalists. Whether the incident was in actuality a Chinese provocation or a false flag operation by the Japanese military was disputed, but the Japanese seized the opportunity and used the incident as the pretext for an invasion of Manchuria.
Given the global conditions of the time, neither the US nor the League of Nations would intervene to prevent the invasion or punish Japan’s blatant violation of the Kellog-Briand Pact. Almost overnight, the pact’s guiding principle of non-aggression had collapsed at the first hurdle. During the 1930s, Italy and Germany, both under fascist rule and both initial signatories, would commit further acts of aggression during the inter-war period, further showcasing the inability of the pact to prevent war.
Upon signing the Kellogg-Briand Pact, Briand declared “The nations of the world will no longer treat war as a lawful means to resolve disputes” and announced that war had been deprived “of its legitimacy”. At the time, the pact appeared to have taken a substantial step towards avoiding another world war, with Kellogg receiving the Nobel Peace Prize in 1929 for his efforts. However, the unravelling of the pact provides a valuable lesson about the nature of international politics: that without a willingness to uphold its terms, international law is powerless to maintain any international order.
The fundamental problem with the Kellogg-Briand Pact was not its noble aims or admirable values, but the lack of any real appetite by world powers to enforce these values. Without a commitment by the Great Powers to safeguard the post-Great War settlement, belligerent powers (like Japan, the Soviet Union, Fascist Italy, and Germany) were incentivized to use the inactivity of other powers to their advantage to rewrite the world order.
The pact represents the prominence of an idealist, progressive foreign policy in the 1920s — and how this idealist thinking quickly unraveled when faced with bad actors and revisionist powers. With the present-day geopolitical scene beset by conflict in Ukraine and the return of war to Europe, this lesson still holds as much relevance today as it did to statesmen of the inter-war period.
