Top Photo: Delegates of the Washington Naval Conference meet in the DAR Building in Washington D.C., November 21, 1921. Exhibitors Herald

Despite being labeled “the war to end all wars,” World War I did not end international conflict forever. Even in its immediate wake, tensions between the United States and Japan in Asia and the Pacific threatened to push these two powerful nations toward armed conflict.

Since the turn of the 20th century, both countries expanded their presence in the Pacific region, especially in China, where the Americans worked to ensure international access to Chinese markets through its “Open Door” policy. They were also building bases for their increasingly large and powerful navies on islands throughout the Pacific, fleets that included massive battleships, the most powerful weapons of the day.

Although both nations took part in World War I, neither saw fighting on their home territory, and both suffered relatively few losses compared to the other major combatants. Both the Japanese and American economies expanded dramatically during the war, and both nations planned to build even more powerful navies to project power in the Pacific. As a member of the victorious Allies, under the Treaty of Versailles Japan also received several colonies in the Pacific that previously belonged to Germany, increasing its strategic footprint in the region.

In addition, there were growing fears at the beginning of the 1920s about the general increase in naval armaments by the world’s leading powers. Besides Japan and the United States, Great Britian and France were both global imperial powers with large navies. Although both suffered massive losses during World War I, Great Britian still had the world’s largest navy, and many feared a repeat of the Anglo-German naval arms race that preceded the war.

It was amid rising tensions over China, Japan’s growing naval power in the Pacific, and fears of an international naval arms race that the Americans convened an international conference in Washington D.C.

This was seemingly a surprising step for the Americans to take; after all, the US Senate had just recently rejected the Treaty of Versailles and voted not to join the new League of Nations. In 1920, American voters elected Warren G. Harding as president. Harding’s view was that it was time for the United States to reexamine its approach to the world after the war, remarking in one speech that “America’s present need is not heroics, but healing; not nostrums but normalcy; not revolution but restoration.”1  

Despite the prevailing narrative that it withdrew from the world after World War I, the Washington Conference on Limitation of Armament, as the Washington Naval Conference was formally titled, is an example of how the United States remained deeply involved in global affairs during the 1920s. In fact, according to historian Warren Cohen, “In the 1920s the United States was more profoundly engaged in international matters than in any peacetime era in its history.”2  

The Conference Begins

On November 12, 1921, exactly three years and a day after the end of World War I, delegates from the United States, Great Britain, Japan, France, Italy, and other countries met in Washington, D.C., to discuss a range of important international security issues.

In his remarks opening the conference, President Harding told his audience of diplomats, reporters, politicians, and other dignitaries that they were “met for a service to mankind” and that “The world demands a sober contemplation of the existing order and the realization that there can be no cure without sacrifice, not by one of us, but by all of us.”3  In other words, the Americans were not just calling on other countries to make sacrifices to preserve peace, they intended to do their part as well.

After Harding’s speech, US Secretary of State Charles Evans Hughes gave his own dramatic address, in which he cautioned against the dangers of continued competition as the world’s major naval powers built larger and ever-more-powerful warships. “One program inevitably leads to another,” he told his audience, warning that “if competition continues its regulation is impracticable. There is only one adequate way out and that is to end it now.”4  

Yet Hughes went further than simply echoing the principles President Harding outlined in his opening statement. He proposed specific steps that the assembled nations, including the United States, should take to reduce their naval forces and prevent the ongoing arms race from deteriorating into armed conflict.

Those steps included eliminating in-progress and planned building programs for capital ships (i.e., battleships and other major warships) and scrapping older vessels that were no longer needed. For the Americans, this meant scrapping six battle cruisers and seven battleships under construction and two battleships already launched; in addition to reducing the size of the American fleet, these steps would also save hundreds of millions of dollars.5

Besides diplomatic and strategic considerations, domestic politics in London, Tokyo, and Washington also shaped the Washington Conference negotiations. Each of the three major countries participating in the conference faced economic and political challenges at home that pushed them to negotiate reductions in their naval arsenals and work to minimize conflict over trade in China and their military installations in the Pacific.

In the United States, loud voices such as the progressive Republican Senator William Borah of Idaho, who later became a prominent supporter of the Neutrality Acts in the 1930s, urged the Harding administration to support arms control legislation that he believed could help prevent another war. Borah was just one of many Americans who favored reducing American involvement abroad in the wake of World War I. Others argued that money spent on capital ships and military preparations could better be better spent at home in the United States on other projects.

Similarly, in Japan, moderate pro-democracy forces accepted the need for naval arms reductions on the grounds that an arms race would place a heavy burden on the Japanese economy. The head of the Japanese delegation to the Washington Conference, Naval Minister Katō Tomosaburō, recognized that mutual arms reductions could work in Japan’s favor: in return for accepting limits on its own naval power, the Americans would have to reduce the size of their fleet, making it less of a threat to Japanese interests in the Pacific.6  

Agreement is Reached

Delegates met and debated in Washington for three months until February 1922. In all, the negotiators concluded three major agreements, which together aimed to reduce tensions in the Asia-Pacific region.

The first treaty, known as the Five-Power Treaty, set a ratio of capital ships for the United States, Great Britain, and Japan at 15:15:10 respectively; the other two signatories, Italy and France, had their ship levels set even lower. In return for their naval strength being set below that of the United States and Britain, the Japanese accepted a pledge from the American and British governments that they would not build up their island possessions in the Pacific into naval bases from which to challenge Japan.

Under the second agreement, the Four-Power Treaty, the signatory powers (the United States, Great Britain, Japan, and France) pledged not to attack one other’s colonies in the Pacific; this agreement replaced an older treaty between Japan and Great Britain.

The final treaty, the Nine-Power Treaty, focused on China, and committed all nine signatories (the US, Britian, Japan, France, Italy, China, the Netherlands, Belgium, and Portugal) to respecting China’s territorial integrity and to refrain from any further imperial acts in that country; it effectively enshrined the American “Open Door” policy into international law.

In a speech before the US Senate praising the treaties and urging their approval, President Harding hopefully proclaimed, “I believe, with all my heart, the powers in conference have combined to make the world [a] safer and better and more hopeful place in which to live.”7

Clifford Berryman cartoon celebrating the end of the Washington Conference on Limitation of Armaments, published in the Washington Star on February 5, 1922

Collectively, the treaties that emerged from the Washington Conference established a dynamic in the Pacific that scholars have called the “Washington Conference system,” where the major powers of the Asia-Pacific region agreed to work together, despite their differences, to preserve peace and stability. But as comprehensive as the three major agreements were, they still left many important issues unresolved. Chief among them was the fact that the naval reductions agreed to by the participants only applied to capital ships (i.e., battleships and heavy cruisers), and did not apply to other types of ships, including smaller cruisers, submarines, and aircraft carriers. This would require additional negotiations, but none of the subsequent conferences were successful in reaching meaningful agreement.

The Collapse of the Washington Conference System

The Washington Conference system operated for most of the 1920s but began to break down by the end of the decade. One major contributor to its demise was the Great Depression, a global economic crisis that hit the United States, Europe, and Japan, where national wealth declined and unemployment reached unprecedented levels. Japan, a nation without major natural resources that was heavily dependent upon imports to keep its economy afloat, was especially hard-hit.

Another factor was a change in leadership in the highest levels of government in Japan, especially within the Imperial Navy. While Katō Tomosaburō, the head of Japan’s delegation to the Washington Conference, had been an ardent supporter of naval reductions, his colleague, Admiral Katō Kanji, took a very different position.

Kanji was part of a younger, more militant faction of officers within the Japanese navy who pushed for a more aggressive foreign policy, one that was much less deferential to the United States. Pushing back against the limitations of the Washington treaties, they called for a more favorable ratio of Japanese to American and British ships, if not outright parity with the two Western naval powers. These officers resisted efforts at the 1930 London Conference to build on the successes of the Washington Conference eight years earlier and successfully opposed new disarmament efforts.

By the early 1930s, these disagreements within the Japanese government deteriorated into outright violence, as zealous Japanese military officers assassinated several politicians they deemed too weak. Under a new militaristic and aggressive regime, the Japanese government unilaterally withdrew from the Five-Power Treaty in 1935, and supporters of the Washington Conference were removed from influential positions. By the middle of the 1930s, the Washington Conference was no longer a sign that the world was getting safer but rather, in the words of historian Sadao Asada, “an important signpost on the road to the Pacific War.”8

The Road to War

Although the Washington Conference concluded nearly two decades before the attack on Pearl Habor, its outcome shaped the course of World War II in the Pacific between the United States and Japan.

By withdrawing from the Five-Power Treaty, Japan was free to build more powerful ships than it was allowed under the Washington Conference system. This step, combined the rise of a military-dominated regime in Tokyo and the Japanese army’s brutal campaign in China, badly damaged relations between Tokyo and Washington, and set the nations on a path to war.

As the 1930s wore on, US-Japanese relations only worsened, to the point where Japanese leaders concluded that their only hope for survival was to launch an aggressive war of conquest to seize the resources their economy needed. To do that, however, they would have to contend with the US Pacific Fleet, which they set out to destroy in December 1941.

In addition to their relevance to the history of World War II, some Americans began reexamining the Washington Conference negotiations during the Cold War. As US negotiators and their Soviet counterparts held extensive talks to reduce the threat of nuclear war, scholars and policymakers alike looked to the 1921-22 conference as an effective example of competing powers coming together to reduce tensions and abolish significant weapons systems.

But whatever positive lessons could be gleaned from the Washington Conference, it also served as a warning about the limitations of arms negotiations. As the journalist Robert Massie wrote in 1977, “Ultimately, we will have peace, not when we have fewer weapons, but when we have grown up enough to realize that war has now become too dangerous a game to play.”9 

• 1

  Warren Harding, “Readjustment,” May 14, 1920, May 14, 1920, Presidential Speeches, The Miller Center, University of Virginia (URL: https://millercenter.org/the-presidency/presidential-speeches/may-14-1920-readjustment). Accessed 10/11/2024.

• 2

  Warren I. Cohen, Empire Without Tears: America’s Foreign Relations 1921-1933 (Philadelphia, PA: Temple University Press, 1987), xii. 

• 3

  Harding, “Opening Speech of the Conference on Limitation of Armament,” November 12, 1921, Presidential Speeches, The Miller Center, University of Virginia (URL: https://millercenter.org/the-presidency/presidential-speeches/november-12-1921-opening-speech-conference-limitation-armament). Accessed 10/1/2024. 

• 4

  Address of Charles E. Hughes, Secretary of State of the Untied State and American Commissioner to the Conference on Limitation of Armaments, Congressional Record—Senate, November 14, 1921, 7637. 

• 5

  Proposal for a Limitation of Naval Armament, Presented by the Secretary of State at the First Plenary Session of the Conference, November 12, 1921, Foreign Relations of the United States (FRUS), 1922, Volume I. (URL: https://history.state.gov/historicaldocuments/frus1922v01/d34). Accessed 10/1/24. 

• 6

  Sadao Asada, From Mahan to Pearl Harbor: The Imperial Japanese Navy and the United States (Annapolis, MD: Naval Institute Press, 2006), 91. 

• 7

  Message of President Harding to the Senate, February 10, 1922, FRUS, 1922, Volume I. (URL: https://history.state.gov/historicaldocuments/frus1922v01/d87). Accessed 10/14/24. 

• 8

  Sadao Asada, “The Revolt Against the Washington Treaty: The Imperial Japanese Navy and Naval Limitation,” Naval War College Review, Vol. 46, NO. 3 (Summer 1993), pp. 95. 

• 9

  Robert K. Massie, “The 1921 SALT Talks – And You Are There,” The New York Times, October 2, 1977.