Humanities › History & Culture Heading Toward World War II in the Pacific Share Flipboard Email Print Keystone / Getty Images History & Culture Military History World War II Battles & Wars Key Figures Arms & Weapons Naval Battles & Warships Aerial Battles & Aircraft Civil War French Revolution Vietnam War World War I American History African American History African History Ancient History and Culture Asian History European History Genealogy Inventions Latin American History Medieval & Renaissance History The 20th Century Women's History View More Table of Contents Expand Japan After World War I Invasion of Manchuria Political Turmoil The Second Sino-Japanese War Begins Conflict With the Soviet Union Foreign Reactions to the Second Sino-Japanese War Moving Towards War With the U.S. Attack on Pearl Harbor Japanese Advances By Kennedy Hickman Military and Naval History Expert M.A., History, University of Delaware M.S., Information and Library Science, Drexel University B.A., History and Political Science, Pennsylvania State University Kennedy Hickman is a historian, museum director, and curator who specializes in military and naval history. He has appeared on The History Channel as a featured expert. our editorial process Facebook Facebook Kennedy Hickman Updated July 28, 2019 World War II in the Pacific was caused by a number of issues stemming from Japanese expansionism to problems relating to the end of World War I. Japan After World War I A valuable ally during World War I, the European powers and the U.S. recognized Japan as a colonial power after the war. In Japan, this led to the rise of ultra-right wing and nationalist leaders, such as Fumimaro Konoe and Sadao Araki, who advocated uniting Asia under the rule of the emperor. Known as hakkô ichiu, this philosophy gained ground during the 1920s and 1930s as Japan needed increasingly more natural resources to support its industrial growth. With the onset of the Great Depression, Japan moved towards a fascist system with the army exerting growing influence over the emperor and government. To keep the economy growing, an emphasis was placed on arms and weapons production, with much of the raw materials coming from the U.S. Rather than continue this dependence on foreign materials, the Japanese decided to seek out resource-rich colonies to supplement their existing possessions in Korea and Formosa. To accomplish this goal, the leaders in Tokyo looked west to China, which was in the midst of a civil war between Chiang Kai-shek's Kuomintang (Nationalist) government, Mao Zedong's Communists, and local warlords. Invasion of Manchuria For several years, Japan had been meddling in Chinese affairs, and the province of Manchuria in northeast China was seen as ideal for Japanese expansion. On Sept. 18, 1931, the Japanese staged an incident along the Japanese-owned South Manchuria Railway near Mukden (Shenyang). After blowing up a section of track, the Japanese blamed the "attack" on the local Chinese garrison. Using the "Mukden Bridge Incident" as a pretext, Japanese troops flooded into Manchuria. The Nationalist Chinese forces in the region, following the government's policy of nonresistance, refused to fight, allowing the Japanese to occupy much of the province. Unable to divert forces from battling the Communists and warlords, Chiang Kai-shek sought aid from the international community and the League of Nations. On Oct. 24, the League of Nations passed a resolution demanding the withdrawal of Japanese troops by Nov. 16. This resolution was rejected by Tokyo and Japanese troops continued operations to secure Manchuria. In January, the U.S. stated that it would not recognize any government formed as a result of Japanese aggression. Two months later, the Japanese created the puppet state of Manchukuo with the last Chinese emperor Puyi as its leader. Like the U.S., the League of Nations refused to recognize the new state, prompting Japan to leave the organization in 1933. Later that year, the Japanese seized the neighboring province of Jehol. Political Turmoil While Japanese forces were successfully occupying Manchuria, there was political unrest in Tokyo. After a failed attempt to capture Shanghai in January, Prime Minister Inukai Tsuyoshi was assassinated on May 15, 1932 by radical elements of the Imperial Japanese Navy who were angered by his support of the London Naval Treaty and his attempts to curb the military's power. Tsuyoshi's death marked the end of civilian political control of the government until after World War II. Control of the government was given to Admiral Saitō Makoto. Over the next four years, several assassinations and coups were attempted as the military sought to gain complete control of the government. On Nov. 25, 1936, Japan joined with Nazi Germany and Fascist Italy in signing the Anti-Comintern Pact which was directed against global communism. In June 1937, Fumimaro Konoe became prime minister and, despite his political leanings, sought to curb the military's power. The Second Sino-Japanese War Begins Fighting between the Chinese and Japanese resumed on a large scale on July 7, 1937, following the Marco Polo Bridge Incident, just south of Beijing. Pressured by the military, Konoe permitted troop strength in China to grow and by the end of the year Japanese forces had occupied Shanghai, Nanking, and southern Shanxi province. After seizing the capital of Nanking, the Japanese brutally sacked the city in late 1937 and early 1938. Pillaging the city and killing nearly 300,000, the event became known as the Rape of Nanking. To combat the Japanese invasion, the Kuomintang and Chinese Communist Party united in an uneasy alliance against the common foe. Unable to effectively confront the Japanese directly in battle, the Chinese traded land for time as they built up their forces and shifted industry from threatened coastal areas to the interior. Enacting a scorched earth policy, the Chinese were able to slow the Japanese advance by mid-1938. By 1940, the war had become a stalemate with the Japanese controlling the coastal cities and railroads and the Chinese occupying the interior and countryside. On Sept. 22, 1940, taking advantage of France's defeat that summer, Japanese troops occupied French Indochina. Five days later, the Japanese signed the Tripartite Pact effectively forming an alliance with Germany and Italy Conflict With the Soviet Union While operations were ongoing in China, Japan became embroiled in border war with the Soviet Union in 1938. Beginning with the Battle of Lake Khasan (July 29 to Aug. 11, 1938), the conflict was a result of a dispute over the border of Manchu China and Russia. Also known as the Changkufeng Incident, the battle resulted in a Soviet victory and expulsion of the Japanese from their territory. The two clashed again in the larger Battle of Khalkhin Gol (May 11 to Sept. 16, 1939) the following year. Led by General Georgy Zhukov, Soviet forces decisively defeated the Japanese, killing over 8,000. As a result of these defeats, the Japanese agreed to the Soviet-Japanese Neutrality Pact in April 1941. Foreign Reactions to the Second Sino-Japanese War Prior to the outbreak of World War II, China was heavily supported by Germany (until 1938) and the Soviet Union. The latter readily provided aircraft, military supplies, and advisors, seeing China as a buffer against Japan. The U.S., Britain, and France limited their support to war contracts prior to the beginning of the larger conflict. Public opinion, while initially on the side of the Japanese, began to shift following reports of atrocities like the Rape of Nanking. It was further swayed by incidents such as the Japanese sinking of the gunboat U.S.S. Panay on Dec. 12, 1937, and increasing fears about Japan's policy of expansionism. U.S. support increased in mid-1941, with the clandestine formation of the 1st American Volunteer Group, better known as the "Flying Tigers." Equipped with U.S. aircraft and American pilots, the 1st AVG, under Colonel Claire Chennault, effectively defended the skies over China and Southeast Asia from late-1941 to mid-1942, downing 300 Japanese aircraft with a loss of only 12 of their own. In addition to military support, the U.S., Britain, and the Netherlands East Indies initiated oil and steel embargoes against Japan in August 1941. Moving Towards War With the U.S. The American oil embargo caused a crisis in Japan. Reliant on the U.S. for 80 percent of its oil, the Japanese were forced to decide between withdrawing from China, negotiating an end to the conflict, or going to war to obtain the needed resources elsewhere. In an attempt to resolve the situation, Konoe asked U.S. President Franklin Roosevelt for a summit meeting to discuss the issues. Roosevelt replied that Japan needed to leave China before such a meeting could be held. While Konoe was seeking a diplomatic solution, the military was looking south to the Netherlands East Indies and their rich sources of oil and rubber. Believing that an attack in this region would cause the U.S. to declare war, they began planning for such an eventuality. On Oct. 16, 1941, after unsuccessfully arguing for more time to negotiate, Konoe resigned as prime minister and was replaced by the pro-military General Hideki Tojo. While Konoe had been working for peace, the Imperial Japanese Navy (IJN) had developed its war plans. These called for a preemptive strike against the U.S. Pacific Fleet at Pearl Harbor, Hawaii, as well as simultaneous strikes against the Philippines, Netherlands East Indies, and the British colonies in the region. The goal of this plan was to eliminate the American threat, allowing Japanese forces to secure the Dutch and British colonies. The IJN's chief of staff, Admiral Osami Nagano, presented the attack plan to Emperor Hirohito on Nov. 3. Two days later, the emperor approved it, ordering the attack to occur in early December if no diplomatic breakthroughs were achieved. Attack on Pearl Harbor On Nov. 26, 1941, the Japanese attack force, consisting of six aircraft carriers, sailed with Admiral Chuichi Nagumo in command. After being notified that diplomatic efforts had failed, Nagumo proceeded with the attack on Pearl Harbor. Arriving approximately 200 miles north of Oahu on Dec. 7, Nagumo began launching his 350 aircraft. To support the air attack, the IJN had also dispatched five midget submarines to Pearl Harbor. One of these was spotted by the minesweeper U.S.S. Condor at 3:42 a.m. outside of Pearl Harbor. Alerted by Condor, the destroyer U.S.S. Ward moved to intercept and sank it around 6:37 a.m. As Nagumo's aircraft approached, they were detected by the new radar station at Opana Point. This signal was misinterpreted as a flight of B-17 bombers arriving from the U.S. At 7:48 a.m., the Japanese aircraft descended on Pearl Harbor. Using specially modified torpedoes and armor piercing bombs, they caught the U.S. fleet by complete surprise. Attacking in two waves, the Japanese managed to sink four battleships and badly damaged four more. In addition, they damaged three cruisers, sank two destroyers, and destroyed 188 aircraft. Total American casualties were 2,368 killed and 1,174 wounded. The Japanese lost 64 dead, as well as 29 aircraft and all five midget submarines. In response, the U.S. declared war on Japan on Dec. 8, after President Roosevelt referred to the attack as "a date which will live in infamy." Japanese Advances Coinciding with the attack on Pearl Harbor were Japanese moves against the Philippines, British Malaya, the Bismarcks, Java, and Sumatra. In the Philippines, Japanese aircraft attacked U.S. and Philippine positions on Dec. 8, and troops began landing on Luzon two days later. Swiftly pushing back General Douglas MacArthur's Philippine and American forces, the Japanese had captured much of the island by Dec. 23. That same day, far to the east, the Japanese overcame fierce resistance from U.S. Marines to capture Wake Island. Also on Dec. 8, Japanese troops moved into Malaya and Burma from their bases in French Indochina. To aid British troops fighting on the Malay Peninsula, the Royal Navy dispatched the battleships H.M.S. Prince of Wales and Repulse to the east coast. On Dec. 10, both ships were sunk by Japanese air attacks leaving the coast exposed. Farther north, British and Canadian forces were resisting Japanese assaults on Hong Kong. Beginning on Dec. 8, the Japanese launched a series of attacks that forced the defenders back. Outnumbered three to one, the British surrendered the colony on Dec. 25.