The Origins of the War in the Pacific

The Second World War—the hegemonic war that forged the international order that has endured for seventy years—was in reality two separate wars. The war in the Pacific had independent origins, which are much more difficult to pin down than the European war. In the present essay, we will examine the origins of the Pacific War. Why did Japan and the United States go to war? What led Japan to attack an adversary many times more powerful than itself?

The Pacific War was a side-show to the polar war in Europe. On the continent, Germany reinitiated a struggle that it had lost not twenty years before. But this time, Hitler held the reigns of German foreign policy. And he was playing for much higher stakes. Germany’s war aims were no longer confined to eliminating France and Russia as great powers and establishing German military supremacy on the continent. Hitler wanted to forge a continental superstate that would be competitive with the United States.* To achieve this goal, the Nazis set upon a genocidal project to clear a vast swarth of territory to the east to make way for German homesteaders.

As opposed to World War I, when Germany won in the east but lost in the west, in World War II, the campaign in the west reached a favourable decision fairly rapidly; allowing the real war to begin in the east. Hitler lost his nerve after the stunning success of the initial campaign. He underestimated the offensive capability of the Wehrmacht and directed it to secure the granary of Ukraine; instead of driving straight to Moscow, as the generals demanded and the men expected. When, after the conquest of Ukraine, Hitler ordered his armies back to Moscow, the cold November rain made the roads impassable to motorized traffic and grounded them to a halt.

After the November crisis, it became a war of attrition. From then on, the die was rigged in favour of Soviet Russia owing to its greater war potential. And once the United States became a Soviet ally, the Allies’ crushing advantage in industrial capability was bound to prove insurmountable. So the Second World War was, in fact, decided very early on.

In the Pacific, the air assault on the US naval base at Pearl Harbor was Japan’s desperate response to the American embargo that guaranteed to eliminate Japan as a great power.

Japanese policymakers knew that an all-out war with the US was utterly hopeless. They reckoned that by a combination of deterrence and appeasement, the United States could be brought to a negotiated settlement that would largely leave Japan in control of its region. Specifically, the Japanese were unwilling to accept the US demand that it withdraw the Kwantung army from the mainland. They wanted to keep at least some of their conquests on the mainland that they had acquired through years of hard fighting. But why on earth did they attack Pearl Harbor? Did they not understand that attacking the US’ main operating base in the Pacific guaranteed that the US would demand unconditional surrender?? And why was the US so insistent on pushing Japan off the mainland in the first place??

The answers are fascinating. The Japanese war council did not, in fact, decide on attacking Pearl Harbor at all. Admiral Yamamoto made the decision at the very last minute and he did not even inform the Cabinet! The only way to keep the Japanese war machine supplied with oil and rubber after the US embargo was to conquer the Dutch East Indies. This was the main goal of the Japanese war strategy. But under the existing war plan, the Imperial Navy’s supply lines would remain exposed to a local counter-attack by US forces located in the western Pacific. Yamamoto gambled that disarming America’s principal naval base in the Pacific would persuade the US to come to terms, instead of galvanizing it to launch an all-out war. Documentary evidence from the United States suggests that FDR would’ve found it very hard to go to war in Asia without a Japanese military assault on US forces. Yamamoto’s reckless gamble effectively terminated Japan’s career as a great power.

And why did the United States embargo Japan? Again, it was not a decision made at the top. It was Assistant Secretary of State for Economic Affairs Dean Acheson who gave the go ahead when FDR was away. When the President found out, he was furious. But being a consummate realist, he figured that back-tracking would signal weakness and let it stand.

But why was the United States considering an embargo on Japan in the first place?

The short answer is that the US was implacably opposed to Japan’s conquest of China. The Japanese had acquired Formosa (Taiwan) in the First Sino-Japanese War (1895), Port Arthur in the Russo-Japanese War (1905), and annexed Korea outright (1910), instead of maintaining it as a protectorate. After World War I, Japan absorbed German territories in the region. Although the US did force Japan to give up a number of positions acquired from the Russians, US policy in Asia consisted of dogged insistence on the Open Door—that no foreign power acquire a preponderant position in China—and little else. In particular, the United States did not forcefully oppose the annexation of Korea that gave Japan a substantial bridgehead on the mainland.

Japan had also established a naval alliance with Britain (1902). At the Washington Naval Conference (1922), the Americans asked the British to dissolve their military alliance with the Japanese in favour of a trilateral naval treaty that pinned the ratio of capital ships at 3:5:5 for Japan, Britain and the US. The rationale offered was that while Japan was confined to the western Pacific, both Great Britain and the United States had to operate in two oceans. Britain and Japan agreed to the terms on offer because they could see that competing for naval primacy with the United States would lead inevitably to financial ruin. During the interwar period, the US had vastly greater economic and financial resources than any other great power.

It has been said that the roots of hot wars lie in cold wars. This is truly the case with the Pacific War. The cold war between the United States and Japan began with the Japanese conquest of Manchuria (1931). The Kwantung army set up the Manchukuo State on the mainland; a puppet state run by the Japanese behind a Manchu façade. The expansion of Japanese influence in China was seen as inconsistent with the Open Door policy in the United States. The British on the other hand, were keen to maintain their alliance with the Japanese. The US responded with the Stimson Doctrine: The United States would refuse to recognize territories forcibly acquired by the Japanese.

Japan also demanded naval parity with the Atlantic powers. But Japanese expansion on the Chinese mainland prompted the US to reject Japanese demands. Japanese-American relations became even more hostile after Japan walked out of the London Naval Conference (1936), loudly declaring its intention to pursue unbounded naval armament.

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The original Japanese interest in Manchuria had been to secure the Southern Manchurian railroad. But the Kwantung army found itself countering Soviet influence in Mongolia and getting pulled into security vacuums in northern China. Sino-Japanese relations had been hostile at least since World War I, when Japan presented the Twenty-One Demands. With Japanese penetration of northern China, they were increasingly conflictual. Skirmishes between the Kwantung army and Chinese forces became increasingly frequent, culminating with the Second Sino-Japanese War (1937).

Japanese forces defeated the regular Chinese forces quickly and decisively. Conventional war with field armies came to an end with the Battle of Nanking in December, 1937. But instead of accepting their Japanese overlords, the Chinese began a guerrilla war under the leadership of Chang Kai-Shek. Japanese forces now faced an adversary that refused to stand and fight. The occupying forces were spread thin and found their lines of communication constantly exposed to ambushes by small raiding parties. Indeed, the Japanese occupation was confined to a few cities.

Pacifiying a hostile land that was vastly larger and much more populous than their own was a near-impossibility. But Japanese industry needed access to China’s resources and markets during a world depression. And the Imperial Japanese Army had its own rapidly expanding demand for matériel in light of the worsening world situation. Besides, the army had gained the upper hand in Japanese high politics by prevailing on the mainland and it was not about to jeopardize its position by acknowledging defeat in the China war.

The United States was, of course, implacably opposed to Japanese domination of China. US policymakers quickly came around to arming Chang Kai-Shek. The war in China became a proxy war pitting Japan against the United States, the Soviet Union, and ultimately, Great Britain. The Soviets had already been fighting a proxy war against the Japanese in Mongolia.

The British, on their part, finally faced up to the incompatibility of their alliance strategy. While they were still hoping to entice Japan away from Germany—the two had become treaty allies in 1936—winning the friendship of the United States was a greater strategic priority in light developments on the continent. And getting British cooperation was absolutely essential to US strategy. The overland route through Xinjiang was completely unviable and the Japanese blockade of the Chinese coast made it impossible to supply the war effort from the sea. The only way to get arms to Chang Kai-Shek was through British-held Burma.


There was nothing inevitable about the Pacific War. The Japanese could’ve not attacked Pearl Harbor and instead run the risk of a military response by US forces in the region. Isolationist sentiment in the United States would likely have prevented FDR from attacking Japan. Earlier on, Japan could’ve come to some sort of accomodation with the United States; for instance, by guaranteeing US access to the Chinese market. Japan would also have been better off abandoning its effort to subdue China once it became clear that it did not have sufficient mass to pacify the land. In that scenario, it would’ve held on to most of its gains and avoided the Second World War altogether.

In the United States, Acheson could’ve obeyed the President’s orders. More generally, Japanese regional primacy was not necessarily inconsistent with US interests. Since national power is barely augmented by colonial posessions (which is why Germany was always stronger than the colonial powers), Japan would’ve remained vastly weaker than the United States. The US could always go to war against Japan in the future, were it ever to threaten a truly vital US interest. Indeed, allowing Japan to dominate the region would’ve thwarted the reemergence of China. Perhaps the United States will pay the price for its misjudgement in the twenty-first century.



* “Whatever comforting, domesticated fantasies their followers may have projected onto them, the leaders of Fascist Italy, National Socialist Germany, Imperial Japan and the Soviet Union all saw themselves as radical insurgents against an oppressive and powerful world order. For all the braggadocio of the 1930s their basic view of the Western Powers was not that they were weak, but that they were lazy and hypocritical. Behind a veneer of morality and panglossian optimism the Western Powers disguised the massive force that had crushed Imperial Germany and that threatened to enshrine a permanent status quo. To forestall that oppressive vision of an end of history would require an unprecedented effort. It would be accompanied by terrible risks. This was the terrifying lesson that the insurgents derived from the story of world politics between 1916 and 1931.” Adam Tooze. The Deluge: The Great War and the Remaking of Global Order 1916-1931.


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