The Pacific War will be covered in a series consisting of nine parts. Our team will publish an article for each part.
Part 1: The Background of the Pacific War
The Seeds of War Are Sown
Around 80 years ago, these two nations, separated by the vast Pacific Ocean, clashed fiercely over the islands scattered across it. In this series, we’ll explore why this war broke out and how it unfolded.
To understand why the Pacific War happened, we need to look at the global context at the time, including the roles of the United States, Japan, and other nations. About 12 years before the war began, the Great Depression struck in October 1929.
The Great Depression (spanning the late 1920s to the 1930s) began with the U.S. stock market crash, plunging the American economy into chaos and triggering a global economic downturn as countries dependent on the U.S.
fell into political and financial turmoil. With goods no longer selling worldwide, Japan was hit hard. Japan had been exporting large quantities of silk to the U.S., but after the Depression, American demand plummeted. When products that once sold well stopped moving, Japan faced a stark reality: without a new strategy, the country would slide deeper into poverty.
Japan’s Territorial Expansion and the Creation of Manchukuo
Facing economic hardship after losing its key trading partner, Japan decided to shift away from reliance on trade and instead build self-sufficiency through territorial expansion. Its first target was China. With its vast land and abundant resources, China was an appealing conquest. At the time, China was in a state of chaos.
The Qing Dynasty, which had once unified the country, had weakened by the early 20th century, leaving China vulnerable. Western powers like Britain, Russia, France, and Germany, which had previously colonized parts of Qing territory, were still vying for control. Meanwhile, internal factions within China further destabilized the nation.
Amid this turmoil, Japan seized the opportunity and took control of Manchuria, a resource-rich region in northeastern China. In 1931, following the staged Mukden Incident, Japan occupied Manchuria and, in 1932, established it as the puppet state of Manchukuo. While Manchukuo was nominally an independent nation, it was effectively under Japanese control.
Japan installed Puyi (Aisin-Gioro Puyi), the last Qing emperor, as its figurehead ruler, but real power rested with Japanese officials stationed there. Key resource-producing areas were nationalized under the pretext of government control, and most of Manchuria’s mined resources—such as coal and iron—were shipped to Japan.
Japan’s Strategy to Dodge International Scrutiny
Japan chose this convoluted approach to avoid backlash from the international community. Manchukuo was established in 1932, just 14 years after the end of World War I in 1918. That war, sparked by Germany’s aggressive expansion into neighboring countries, had claimed over 16 million lives (military and civilian combined).
In its aftermath, a global consensus emerged: “Enough with wars—taking other nations’ territory only leads to more conflict.” Japan, reeling from the Great Depression and desperate to secure resources, was well aware of this anti-expansionist sentiment.
Rather than boldly declaring Manchuria a part of Japan, Tokyo opted for a façade: Manchukuo would appear as an independent state carved out of China, while remaining firmly under Japanese influence. China, however, refused to recognize this “absurd nation” and clashed with Japan over it.
Small-scale skirmishes broke out frequently between Japanese troops stationed in Manchuria and local Chinese forces. These escalating conflicts eventually spiraled into full-scale war between Japan and China, known as the Second Sino-Japanese War, which began in earnest on July 7, 1937, following the Marco Polo Bridge Incident. We’ll cover this war in greater detail later—it became a grueling, muddy quagmire for both sides.
The Second Sino-Japanese War and the International Response
Japan captured Nanjing, then China’s capital, in December 1937, but China refused to surrender. Even after losing its capital, China relocated its government (to Chongqing) and fought on tenaciously. The conflict dragged on far longer than Japan had anticipated. China’s dogged resistance stemmed from its keen awareness of the international climate.
Japan’s forcible creation of Manchukuo and the ensuing war had drawn sharp criticism from the global community, and China believed that prolonging the fight might garner support from Western powers opposed to Japan’s aggression.
Western nations, which had exploited China since the Qing era, viewed Japan’s war and monopolization of Manchuria as excessive. A sentiment emerged: “Japan needs to be taught a lesson.” As China had hoped, this translated into economic sanctions against Japan and aid for China. In 1940–1941, the United States imposed embargoes on critical exports like steel and oil to Japan.
The Soviet Union (modern-day Russia) sent weapons to China, and Britain also provided assistance. Japan had expected to swiftly defeat China, but it found itself not only battling China but also indirectly facing giants like the U.S., the Soviet Union, and Britain.
Japan’s Dilemma and the Spark of the Pacific War
Japan concluded that to force China’s surrender, it first needed to cut off this Western support. Negotiations with the Allied powers ensued but quickly stalled. The U.S. demanded that Japan return Manchukuo to China, withdraw all troops from Chinese territory, and abandon exclusive trade privileges with China in favor of equal trade access for all nations. If Japan refused, the U.S. warned, economic sanctions would tighten further.
For Japan, yielding to these demands was unthinkable. By 1941, thousands of Japanese settlers had moved to Manchuria, and the nation had poured immense resources and effort into both Manchukuo and the war with China.
Backing down now would render all that investment and sacrifice meaningless. Japan faced a stark choice: abandon Manchuria and its ambitions under U.S. pressure, or wage all-out war against the Western powers to secure total control over China.
In the end, Japan chose war. Feeling cornered with no room to retreat, it launched a surprise attack on Pearl Harbor on December 7, 1941, igniting the Pacific War against the United States and its allies.