The Early War in the Pacific

Japanese Aggression

Beginning in the 1930s, Japan aggressively expanded the territories under its influence, taking over parts of China, invading territories claimed by the Soviet Union, and fighting across the Pacific during World War II.

Learning Objectives

Discuss the Japanese invasions of Manchuria, China, and the Soviet Union in the 1930s

Key Takeaways

Key Points

  • In 1931, Japan invaded Manchuria and established a puppet regime there. In 1936, they established a similar puppet regime in Mongolia.
  • In 1937, Japan invaded China, launching the Second Sino-Japanese war, a conflict between Japan, Mao Zedong ‘s communists, and Chiang Kai-shek’s nationalists. The war later merged into the larger World War II conflict.
  • Throughout late 1941 and early 1942, Japan invaded Southeast Asia, successfully capturing Hong Kong, British Malaya, and the Philippines.
  • The Japanese also seized the key oil production zones of Borneo, Central Java, Malang, Cepu, Sumatra, and Dutch New Guinea of the late Dutch East Indies, defeating the Dutch forces.
  • The Battle of Coral Sea and the Battle of Midway in 1942 represented crucial losses for the Japanese and marked a turning point in the war.

Key Terms

  • Mukden Incident: A staged event engineered by Japanese military personnel as a pretext for the Japanese invasion in 1931 of northeastern China, known as Manchuria.
  • Second Sino-Japanese War: A military conflict fought primarily between the Republic of China and the Empire of Japan
    from July 7, 1937, to September 2, 1945. It was the largest Asian war in the 20th century and it made up more than 50 percent of the casualties in the Pacific War (if the 1937–1941 period is taken into account).
  • Mao Zedong: A Chinese Communist revolutionary, guerrilla warfare strategist, anti-imperialist political philosopher, and leader of the Chinese Revolution. He was the architect and founding father of the People’s Republic of China (PRC) from its establishment in 1949, and held authoritarian control over the nation until his death in 1976. His theoretical contribution to Marxism–Leninism, along with his military strategies and brand of policies, are collectively known as Maoism.
  • Chiang Kai-Shek: A 20th-century Chinese political and military leader. He was an influential member of the Kuomintang (KMT), or the Chinese Nationalist Party. In the Chinese civil war, the KMT fought against the Communist Party of China (CPC). The CPC defeated the Nationalists in 1949, forcing his government to retreat to Taiwan. After evacuating to Taiwan, his government continued to declare its intention to retake mainland China. The U.S. recognized the KMT as the legitimate government of China, rather than recognize the CPC.
  • Nanking Massacre: A massacre of up to 300,000 Chinese civilians and disarmed combatants by the Japanese, executed after the fall of Nanking during the six weeks following December 13, 1937.

Manchuria

In the 1920s and 1930s, the Japanese Empire’s main economic problem was the lack of sufficient raw materials. Japan needed to import raw materials such as iron, rubber, and oil to maintain strong economic growth. The Japanese felt that acquiring resource-rich territories would establish economic self-sufficiency and independence, and they also hoped to jump-start the nation’s economy in the midst of the Great Depression. As a result, Japan set its sights on East Asia, specifically Manchuria, with its many resources.

On September 18, 1931, in what is known as the Mukden Incident, Lt. Suemori Kawamoto detonated a small quantity of dynamite close to a railway line owned by Japan’s South Manchuria Railway near Mukden (now Shenyang). The explosion was so weak that it failed to destroy the track and a train passed over it minutes later, but the Imperial Japanese Army accused Chinese dissidents of the act and responded with a full invasion. A day later, Japan invaded Manchuria. It claimed that the invasion was a liberation of the Manchus from the Chinese, although the majority of the population were Han Chinese as a result of the large-scale settlement of Chinese in Manchuria in the 19th century. A puppet regime called Manchukuo was established with little resistance. Jehol, a Chinese territory bordering Manchuria, was taken in 1933. Japan had withdrawn from the League of Nations earlier that year and the events led to no specific actions from the international community.

In 1936, Japan also created a Mongolian puppet state in Inner Mongolia named Mengjiang, which was also predominantly Chinese as a result of recent Han immigration to the area.

China

In 1937, Japan invaded China, starting what was essentially a three-way war between Japan, Mao Zedong’s communists, and Chiang Kai-shek’s nationalists. The invasion began what would become known as the Second Sino-Japanese War, which after the Japanese attack on Pearl Harbor in 1941 would merge into the greater conflict of World War II as a major front of what is broadly known as the Pacific War.

Building on the hard-won victory in Shanghai, the Japanese army captured the Chinese nationalist capital city of Nanjing (Nanking) and Northern Shanxi by the end of 1937, in campaigns involving approximately 350,000 Japanese soldiers and considerably more Chinese. After the fall of Nanking on December 13, what would become known as the Nanking Massacre began and lasted over the period of the next six weeks. Historians estimate up to 300,000 Chinese civilians and disarmed combatants were mass murdered in the process. Because of the widespread systematic use of rape, the events are also known as the “Rape of Nanking.” Historians estimate that, in addition to children and the elderly, around 20,000 women were raped. Records of eyewitnesses demonstrate a massive scale of brutal violence. Until today, some Japanese deny the atrocities ever occurred.

The Second Sino-Japanese War was the largest Asian war in the 20th century. It accounted for the majority of civilian and military casualties in the Pacific War, with anywhere between 10 and 25 million Chinese civilians and over 4 million Chinese and Japanese military personnel dying from war-related violence, famine, and other causes. By the end of the Pacific War, Japan had conquered much of the Far East, including Hong Kong, Vietnam, Cambodia, Myanmar, the Philippines, Indonesia, part of New Guinea, and some islands of the Pacific Ocean.

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A map of the Japanese advance from 1937 to 1942

Soviet Union

In 1938, the Japanese 19th Division entered territory claimed by the Soviet Union, leading to the Battle of Lake Khasan. This incursion was founded in the Japanese belief that the Soviet Union misinterpreted the demarcation of the boundary, as stipulated in the Treaty of Peking, between Imperial Russia and Manchu China. On May 11, 1939, in the Nomonhan Incident (Battle of Khalkhin Gol), a Mongolian cavalry unit of some 70 to 90 men entered the disputed area. The Japanese also became involved. Joseph Stalin ordered development of a plan for a counter-strike against the Japanese, which resulted in massive Japanese losses. On September 15, an armistice was arranged. Nearly two years later, on April 13, 1941, the parties signed a Neutrality Pact, in which the Soviet Union pledged to respect the territorial integrity and inviolability of Manchukuo, while Japan agreed similarly for the Mongolian People’s Republic.

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Japanese occupation: Map showing the extent of Japanese control (purple) in 1940.

World War II

On September 27, 1940, Imperial Japan signed the Tripartite Pact with Nazi Germany and Fascist Italy, establishing what would become known as the Axis powers. The pact called for mutual protection and technological and economic cooperation.

Facing an oil embargo by the United States as well as dwindling domestic reserves, the Japanese government decided to attack Pearl Harbor, Oahu, Hawaii, on December 7, 1941, leading to significant losses for the U.S. Navy and air forces. The objective of the attack was to incapacitate the U.S. long enough for Japan to establish its Southeast Asian empire and defensible buffer zones. The United States entered the European Theatre and Pacific Theater in full force. Four days later, Adolf Hitler of Nazi Germany and Benito Mussolini of Italy declared war on the United States, merging the separate conflicts.

Following Pearl Harbor, the Japanese launched offensives against Allied forces in Southeast Asia, with simultaneous attacks on Hong Kong, British Malaya, and the Philippines. Hong Kong surrendered to the Japanese on December 25, 1941. The Japanese forced the Allies in Malaya to retreat into Singapore and on February 15, 1942, Singapore fell to the Japanese, causing the largest surrender of British-led military personnel in history. The Japanese military carried out a purge of the Chinese population in Malaya and Singapore and are believed to have killed tens of thousands of ethnic Chinese. In the Philippines, the Japanese pushed the combined Filipino-American force towards the Bataan peninsula and later the island of Corregidor. January 1942 marked one of the worst defeats suffered by the Americans, leaving over 70,000 American and Filipino prisoners of war in the custody of the Japanese.

The Japanese also seized the key oil production zones of Borneo, Central Java, Malang, Cepu, Sumatra, and Dutch New Guinea of the late Dutch East Indies, defeating the Dutch forces. They also consolidated their lines of supply through capturing key islands of the Pacific, including Guadalcanal.

In May 1942, the Japanese failed to defeat the Allies at the Battle of the Coral Sea, despite numerical superiority, and in June 1942, they lost a four-carrier task force at the Battle of Midway. Midway was a decisive defeat for the Japanese and proved to be the turning point of the war. In September 1942, they were defeated by Australians in New Guinea at the Battle of Milne Bay. Further defeats by the Allies at Guadalcanal in September 1942, and New Guinea in 1943, put the empire of Japan on the defensive for the remainder of the war.

Attack on Pearl Harbor

The attack on Pearl Harbor, a surprise military strike conducted by Japan on December 7, 1941, forced the United States to formally enter World War II.

Learning Objectives

Describe both the motivations and the effects of the Japanese attack on Pearl Harbor

Key Takeaways

Key Points

  • Facing the problem of insufficient natural resources and following the ambition to become a major global power, the Japanese Empire began aggressive expansion in the 1930s.
  • Although negotiations aiming to improve relations between Japan and the United States were still ongoing, the Imperial Japanese Navy attacked the U.S. naval base at Pearl Harbor, Hawaii, on the morning of December 7, 1941.
  • Three hundred and fifty Japanese planes attacked eight battleships, killing more than 2,400 and injuring over 1,100 Americans.
  • In the aftermath of the events, the United States declared war on Japan a day after the attack. Because of the Tripartite Pact, Germany and Italy declared war on the United States on December 11.
  • The attack came as a shock to the American public and anti-Japanese sentiments grew dramatically. Internment camps were established to imprison Japanese American residents and citizens.

Key Terms

  • Tripartite Pact: A treaty signed in Berlin, Germany, on September 27, 1940, which established the Axis powers of World War II. The pact was signed by representatives of Nazi Germany (Adolf Hitler), Fascist Italy (foreign minister Galeazzo Ciano), and Imperial Japan (Japanese ambassador to Germany Saburo Kurusu).
  • Pearl Harbor: A United States Navy deep-water naval base in Hawaii and the headquarters of the U.S. Pacific Fleet. The attack on it by the empire of Japan on Sunday, December 7, 1941, brought the United States into World War II.
  • internment camp: A prison camp for the confinement of enemy aliens (actual or individuals percieved as such), prisoners of war, or political prisoners.

The attack on Pearl Harbor was a surprise military strike conducted by the Imperial Japanese Navy against the United States naval base at Pearl Harbor, Hawaii, on the morning of December 7, 1941. The attack was intended as a preventive action in order to keep the U.S. Pacific Fleet from interfering with military actions the empire of Japan was planning in Southeast Asia against overseas territories of the United Kingdom, the Netherlands, and the United States.

Motivations

Facing the problem of insufficient natural resources and following the ambition to become a major global power, the Japanese Empire began aggressive expansion in the 1930s. In 1931, Japan invaded and conquered Manchuria, and Jehol, a Chinese territory bordering Manchuria, was taken in 1933. In 1936, Japan also created a Mongolian puppet state in Inner Mongolia named Mengjiang. In 1937, Japan invaded China, starting what would become known as the Second Sino-Japanese War. After the Japanese attack on Pearl Harbor, the war would merge into the greater conflict of World War II as a major front of what is broadly known as the Pacific War.

In 1940, Japan invaded French Indochina in an effort to control supplies reaching China. Following Japanese expansion into Indochina and the fall of France, in July 1941, the U.S. ceased oil exports to Japan. This caused the Japanese to proceed with plans to take the Dutch East Indies, an oil-rich territory. Following the developments, Japan and the U.S. engaged in negotiations in an effort to improve relations. After exchanging a series of conditions, Japan presented its final proposal. On November 20, 1941, it offered to withdraw forces from southern Indochina and not to launch any attacks in Southeast Asia provided that the U.S., the UK, and the Netherlands ceased aiding China and lifted their sanctions against Japan. The American counterproposal of November 26 required Japan to evacuate all of China without conditions and conclude non-aggression pacts with Pacific powers. However, the day before the proposal was delivered (November 27), the main Japanese attack fleet left port for Pearl Harbor.

Attack

The base was attacked by 353 Japanese fighters, bombers, and torpedo planes in two waves, launched from six aircraft carriers. All eight U.S. Navy battleships were damaged, and four were sunk. Of the eight damaged, two were raised, and with four repaired, six battleships returned to service later in the war. The Japanese also sank or damaged three cruisers, three destroyers, an anti-aircraft training ship, and one mine layer. In all, 188 U.S. aircraft were destroyed, 2,402 Americans were killed and 1,282 wounded. Important base installations such as the power station, shipyard, maintenance, and fuel and torpedo storage facilities, as well as the submarine piers and headquarters building (also home of the intelligence section) were not attacked. Japanese losses were light: 29 aircraft and five midget submarines lost. Sixty five servicemen killed or wounded and one Japanese sailor was captured.

Effect

The attack came as a profound shock to the American people and led directly to the American entry into World War II in both the Pacific and European theaters. The following day (December 8), the United States declared war on Japan. Domestic support for non-interventionism, which had been traditionally strong and fading since the fall of France in 1940, disappeared. Clandestine support of Britain (for example the Neutrality Patrol) was replaced by active alliance. Subsequent operations by the U.S. prompted Germany and Italy to declare war on the U.S. on December 11, which was reciprocated by the U.S. the same day.

One of the most controversial consequences of the attack was the creation of internment camps for Japanese American residents and citizens. Within hours of the attack, hundreds of Japanese American leaders were rounded up and brought to high-security camps such as Sand Island at the mouth of Honolulu Harbor and Kilauea Military Camp on the island of Hawaii. Roosevelt authorized the deportation and incarceration with Executive Order 9066, issued February 19, 1942. Over 110,000 Japanese Americans, including United States citizens, were removed from their homes and transferred to internment camps in California, Idaho, Utah, Arizona, Wyoming, Colorado, New Mexico, Arkansas, and Texas. Many historians see the decision as one of the most shameful chapters in the history of the Roosevelt administration.

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Battleship USS California sinking, December 7, 1941, National Archives and Records Administration: The U.S. Navy battleship USS California (BB-44) slowly sinking alongside Ford Island, Pearl Harbor, Hawaii (USA), as a result of bomb and torpedo damage, December 7, 1941. The destroyer USS Shaw (DD 373) is burning in the floating dry dock YFD-2 in the left distance. The battleship USS Nevada (BB-36) is beached in the left-center distance.

Coral Sea and Midway

The Battle of the Coral Sea and the Battle of Midway were strategic triumphs for the Allies and marked the critical point in halting Japanese expansion during World War II.

Learning Objectives

Examine the importance of the Battle of the Coral Sea and the Battle of Midway as turning points for the Allies

Key Takeaways

Key Points

  • In an attempt to defend their empire in the South Pacific, Imperial Japanese forces decided to invade and occupy Port Moresby in New Guinea and Tulagi in the southeastern Solomon Islands.
  • The Battle of the Coral Sea, May 4–8, 1942, was a major naval battle in the Pacific Theater of World War II between the Imperial Japanese Navy and Allied naval and air forces from the United States and Australia.
  • It was the first naval engagement in history in which the participating ships did not fire directly at each other, as aircraft acted as the offensive artillery for the ships involved.
  • Although a tactical victory for the Japanese in terms of ships sunk, the battle would prove to be a strategic victory for the Allies.
  • A month later, the Battle of Midway, a decisive naval battle in the Pacific Theater of World War II, was fought between June 4 and 7, 1942. The United States Navy decisively deflected an Imperial Japanese Navy (IJN), inflicting irreparable damage on the Japanese fleet.
  • Following the Japanese defeat at Midway, the Allies took advantage of Japan’s vulnerability in the South Pacific and launched the Guadalcanal Campaign, a significant contributing factor to Japan’s ultimate defeat in World War II.

Key Terms

  • Solomon Islands campaign: A major campaign of the Pacific War of World War II that began with Japanese landings and occupation of several areas in the British Solomon Islands and Bougainville, in the Territory of New Guinea, during the first six months of 1942.
  • Battle of Midway: A decisive naval battle in the Pacific Theater of World War II. Between June 4 and 7, 1942, the United States Navy decisively deflected an Imperial Japanese Navy (IJN) attack against Midway Atoll, inflicting irreparable damage on the Japanese fleet.
  • Guadalcanal Campaign: A military campaign fought between August 7, 1942, and February 9, 1943, on and around the island of Guadalcanal in the Pacific Theater of World War II. It was the first major offensive by Allied forces against the empire of Japan and a significant strategic combined arms victory by Allied forces over the Japanese in the Pacific Theater.
  • Battle of the Coral Sea: A major naval battle in the Pacific Theater of World War II between the Imperial Japanese Navy and Allied naval and air forces from the United States and Australia, fought May 4–8, 1941. Although a tactical victory for the Japanese in terms of ships sunk, the battle would prove to be a strategic victory for the Allies.

The Battle of the Coral Sea

The Battle of the Coral Sea, May 4–8, 1942, was a major naval battle in the Pacific Theater of World War II between the Imperial Japanese Navy and Allied naval and air forces from the United States and Australia. The battle was the first action in which aircraft carriers engaged each other, as well as the first in which neither side’s ships sighted or fired directly upon the other.

In an attempt to defend their empire in the South Pacific, Imperial Japanese forces decided to invade and occupy Port Moresby in New Guinea and Tulagi in the southeastern Solomon Islands. The plan to accomplish this, called Operation MO, involved several major units of Japan’s Combined Fleet. The U.S. learned of the Japanese plan through signals intelligence and sent two United States Navy carrier task forces and a joint Australian-American cruiser force to oppose the Japanese offensive.

On May 3–4, Japanese forces successfully invaded and occupied Tulagi, although several of their supporting warships were surprised and sunk or damaged by aircraft from the U.S. fleet carrier Yorktown. Now aware of the presence of U.S. carriers in the area, the Japanese fleet carriers entered the Coral Sea with the intention of finding and destroying the Allied naval forces.

Beginning on May 7, the carrier forces from the two sides exchanged airstrikes over two consecutive days. With both sides having suffered heavy losses in aircraft and carriers damaged or sunk, the two fleets disengaged and retired from the battle area. Although a tactical victory for the Japanese in terms of ships sunk, the battle would prove to be a strategic victory for the Allies for several reasons. Japanese expansion, seemingly unstoppable until then, was turned back for the first time. More importantly, the Japanese fleet carriers Shōkaku and Zuikaku—one damaged and the other with a depleted aircraft complement—were unable to participate in the Battle of Midway, which took place the following month, ensuring a rough parity in aircraft between the two adversaries and contributing significantly to the U.S. victory in that battle. The severe losses in carriers at Midway prevented the Japanese from reattempting to invade Port Moresby from the ocean.

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Collage of the Battle of Midway: Top left: Two Mitsubishi A6M2a Zero of the Imperial Japanese Navy Aviation in China (May 26, 1941). Top right: The Japanese aircraft carrier Hiryu burning and sinking the morning after being bombed by U.S. aircraft during the Battle of Midway on June 5, 1942. Bottom left: U.S. aircraft carrier USS Yorktown (CV-5) burning after the first Japanese aircraft attack at Midway. Bottom right: Flight deck of USS Hornet (CV-8) on the morning of June 4, 1942.

The Battle of the Midway

The Battle of Midway was a decisive naval battle in the Pacific Theater of World War II. Between June 4 and 7, 1942, six months after Japan’s attack on Pearl Harbor and one month after the Battle of the Coral Sea, the United States Navy decisively deflected an Imperial Japanese Navy attack against Midway Atoll, inflicting irreparable damage on the Japanese fleet.

The operation, like the earlier attack on Pearl Harbor, sought to eliminate the United States as a strategic power in the Pacific, thereby giving Japan a free hand in establishing its Greater East Asia Co-Prosperity Sphere. The Japanese hoped another demoralizing defeat would force the U.S. to capitulate in the Pacific War. Luring the American aircraft carriers into a trap and occupying Midway was part of an overall “barrier” strategy to extend Japan’s defensive perimeter, in response to the Doolittle air raid on Tokyo. This operation was also considered preparatory for further attacks against Fiji, Samoa, and Hawaii.

The plan was handicapped by faulty Japanese assumptions of the American reaction and poor initial dispositions. Most significantly, American code-breakers were able to determine the date and location of the attack, enabling the forewarned U.S. Navy to set up an ambush of its own. Four Japanese aircraft carriers—Akagi, Kaga, Soryu, and Hiryu, all part of the six-carrier force to launch the attack on Pearl Harbor six months earlier—were sunk for a cost of one American aircraft carrier and a destroyer. After Midway and the exhausting attrition of the Solomon Islands campaign, Japan’s shipbuilding and pilot training programs were unable to keep pace in replacing their losses while the U.S. steadily increased its output in both areas.

The Battle of Midway has often been called “the turning point of the Pacific.” It was the Allies’ first major naval victory against the Japanese. Although the Japanese continued to try to secure more territory, and the U.S. did not move from a state of naval parity to one of supremacy until after several more months of hard combat, Midway allowed the Allies to switch to the strategic initiative, paving the way for the landings on Guadalcanal and the prolonged attrition of the Solomon Islands campaign.

The Guadalcanal Campaign

The Guadalcanal Campaign of 1942–43 became a crucial victory by Allied forces in the Pacific.

Learning Objectives

Summarize the strategy and Allied victory of the Guadalcanal Campaign

Key Takeaways

Key Points

  • After the 1941 attack on Pearl Harbor, Japan significantly expanded its control over multiple territories in the Pacific region. By securing the southern Solomon Islands, the Japanese aimed to destroy supply and communication routes between the U.S., Australia, and New Zealand.
  • Allied forces achieved a decisive victory in November 1942 at the Naval Battle of Guadalcanal. In February 1943, the Japanese forces completed their evacuation from Guadalcanal.
  • This campaign ended all Japanese expansion attempts and placed the Allies in a position of military and psychological supremacy.

Key Terms

  • Battle of the Coral Sea: A major naval battle in the Pacific Theater of World War II between the Imperial Japanese Navy and Allied naval and air forces from the United States and Australia, fought May 4–8, 1941. Although a tactical victory for the Japanese in terms of ships sunk, the battle would prove to be a strategic victory for the Allies.
  • Battle of Midway: A decisive naval battle in the Pacific Theater of World War II. Between June 4 and 7, 1942, the United States Navy decisively deflected an Imperial Japanese Navy (IJN) attack against Midway Atoll, inflicting irreparable damage on the Japanese fleet.
  • Tulagi: A small island in the Solomon Islands, just off the south coast of Florida Island. The Japanese occupied it on May 3, 1942, with the intention of setting up a seaplane base nearby; however, the Japanese ships were raided by planes from the USS Yorktown the following day in a prelude to the Battle of the Coral Sea.
  • Solomon Islands: A sovereign state in Oceania, east of Papua New Guinea, consisting of nearly 1,000 islands. Some of the most intense fighting of World War II occurred there, particularly the most significant of the Allied forces’ operations against the Japanese Imperial Forces, which were launched on August 7, 1942, with simultaneous naval bombardments and amphibious landings on the Florida Islands at Tulagi and Red Beach on Guadalcanal.
  • Guadalcanal: A tropical island in the Southwestern Pacific. During 1942–43, it was the scene of bitter fighting between Japanese and American troops; the American forces were ultimately victorious.

The Guadalcanal Campaign, also known as the Battle of Guadalcanal and code-named Operation Watchtower, was a military campaign fought between August 7, 1942, and February 9, 1943, on and around the island of Guadalcanal in the Pacific Theater of World War II. It was the first major offensive by Allied forces against the empire of Japan.

Background

The 1941 Japanese attack on Pearl Harbor crippled much of the U.S. battleship fleet and precipitated an open and formal state of war between the two nations. The initial goals of Japanese leaders were to neutralize the United States Navy, seize possessions rich in natural resources, and establish strategic military bases to defend Japan’s empire in the Pacific Ocean and Asia. To further those goals, Japanese forces captured the Philippines, Thailand, Malaya, Singapore, Burma, the Dutch East Indies, Wake Island, Gilbert Islands, New Britain, and Guam. Joining the U.S. in the war against Japan were the rest of the Allied powers, several of whom, including the United Kingdom, Australia, and the Netherlands, had also been attacked by Japan.

Further attempts by the Japanese to continue their strategic initiative and offensively extend their outer defensive perimeter in the south and central Pacific were thwarted at the naval battles of the Coral Sea (May 1941) and Midway (June 1941) respectively. Up to this point, the Allies had been on the defensive in the Pacific, but these strategic victories provided them an opportunity to seize the initiative from Japan.

The Allies chose the Solomon Islands (a protectorate of the United Kingdom), specifically the southern Solomon Islands of Guadalcanal, Tulagi  and Florida Island, as the first target. The Imperial Japanese Navy had occupied Tulagi in May 1942, and had constructed a seaplane base nearby. Allied concern grew when, in early July 1942, the IJN began constructing a large airfield at Lunga Point on nearby Guadalcanal—from such a base, Japanese long-range bombers would threaten the sea lines of communication from the West Coast of the Americas to the populous East Coast of Australia. By August 1942, the Japanese had about 900 naval troops on Tulagi and nearby islands and 2,800 personnel on Guadalcanal.

Campaign

On August 7, 1942, Allied forces, predominantly American, landed on the islands of Guadalcanal, Tulagi, and Florida in the southern Solomon Islands, with the objective of denying their use by the Japanese to threaten the supply and communication routes between the U.S., Australia, and New Zealand. The Allies also intended to use Guadalcanal and Tulagi as bases to support a campaign to eventually capture or neutralize the major Japanese base at Rabaul on New Britain. The Allies overwhelmed the outnumbered Japanese defenders, who had occupied the islands since May 1942, and captured Tulagi and Florida as well as an airfield (later named Henderson Field) that was under construction on Guadalcanal. Powerful U.S. naval forces supported the landings.

Surprised by the Allied offensive, the Japanese made several attempts between August and November of 1942 to retake Henderson Field. Three major land battles, seven large naval battles, and continual, almost daily aerial battles, culminated in the decisive Naval Battle of Guadalcanal in early November 1942. The last Japanese attempt to bombard Henderson Field from the sea and land with enough troops to retake it was defeated. In December 1942, the Japanese abandoned further efforts to retake Guadalcanal and evacuated their remaining forces by February 7, 1943, in the face of an offensive by the U.S. Army’s XIV Corps, conceding the island to the Allies.

Effect

The Guadalcanal Campaign was a significant strategic combined arms victory by Allied forces over the Japanese in the Pacific Theater. The Japanese had reached the high-water mark of their conquests in the Pacific, and Guadalcanal marked the transition by the Allies from defensive operations to the strategic offensive in that theater and the beginning of offensive operations, including the Solomon Islands, New Guinea, and Central Pacific campaigns, that resulted in Japan’s eventual surrender and the end of World War II.

Perhaps as important as the military victory for the Allies was the psychological victory. On a level playing field, the Allies had beaten Japan’s best land, air, and naval forces. After Guadalcanal, Allied personnel regarded the Japanese military with much less fear and awe than previously. In addition, the Allies viewed the eventual outcome of the Pacific War with greatly increased optimism.

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Pacific Theater Areas: Japanese control of the western Pacific area between May and August 1942. Guadalcanal is located in the lower right center of the map.