The Pacific War



Pearl Harbor

The attack on Pearl Harbor was a surprise military strike by the Imperial Japanese Navy against the United States naval base on the morning of December 7, 1941, which led to the U.S. entry into World War II.

Learning Objectives

Evaluate the effect the attack on Pearl Harbor had on the American nation

Key Takeaways

Key Points

  • Japan intended the attack on Pearl Harbor as a preventive action to keep the U.S. Pacific Fleet from interfering with military actions the Empire of Japan planned in Southeast Asia against overseas territories of the United Kingdom, the Netherlands, and the United States.
  • During the attacks, 188 U.S. aircraft were destroyed, 2,403 Americans were killed, and 1,178 others were wounded.
  • The attack came as a profound shock to the American people and led directly to the U.S. entry into World War II in both the Pacific and European theaters.
  • Subsequent operations by the U.S. prompted Nazi Germany and Fascist Italy to declare war on the U.S. on December 11, reciprocated by the U.S. the same day.

Key Terms

  • Nanking Massacre: An episode of mass murder and mass rape committed by Japanese troops against the residents of Nanking, then the capital of the Republic of China during the Second Sino-Japanese War.
  • Tripartite Pact: A defensive military alliance between Germany, Japan, and Italy signed in Berlin on September 27, 1940.

The attack on Pearl Harbor was a surprise military strike by the Imperial Japanese Navy against the United States naval base at Pearl Harbor, Hawaii Territory, on the morning of December 7, 1941. The attack led to the U.S. entry into World War II.

Japan intended the attack as a preventive action to keep the U.S. Pacific Fleet from interfering with military actions the Empire of Japan planned in Southeast Asia against overseas territories of the United Kingdom, the Netherlands, and the U.S. Over the next seven hours there were coordinated Japanese attacks on the U.S.-held Philippines, Guam, and Wake Island and on the British Empire in Malaya, Singapore, and Hong Kong.

The Day of the Attack

At 7:48 a.m. Hawaiian Time, the base was attacked by 353 Imperial Japanese fighter planes, bombers, and torpedo planes in two waves, launched from six aircraft carriers. All eight U.S. Navy battleships were damaged and four sunk. All but the USS Arizona (BB-39) were later raised, and six were returned to service and went on to fight in the war. The Japanese also sank or damaged three cruisers, three destroyers, an anti-aircraft training ship, and one minelayer. 188 U.S. aircraft were destroyed, 2,403 Americans were killed, and 1,178 others were 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 and 64 servicemen killed. One Japanese sailor, Kazuo Sakamaki, was captured.

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 fading since the Fall of France in 1940, disappeared entirely. Clandestine support of the United Kingdom (e.g., the Neutrality Patrol) was replaced by active alliance. Subsequent operations by the U.S. prompted Nazi Germany and Fascist Italy to declare war on the U.S. on December 11, reciprocated by the U.S. the same day.

There were numerous historical precedents for unannounced military action by Japan. However, the lack of any formal warning, particularly while negotiations were still apparently ongoing, led President Franklin D. Roosevelt to proclaim December 7, 1941, “a date which will live in infamy.” Because the attack happened without a declaration of war and without explicit warning, the attack on Pearl Harbor was judged by the Tokyo Trials to be a war crime.

Photograph taken from a Japanese plane during the torpedo attack on ships moored on both sides of Ford Island shortly after the beginning of the Pearl Harbor attack. View looks about east, with the supply depot, submarine base and fuel tank farm in the right center distance. A torpedo has just hit USS West Virginia on the far side of Ford Island (center). Other battleships moored nearby are (from left): Nevada, Arizona, Tennessee (inboard of West Virginia), Oklahoma (torpedoed and listing) alongside Maryland, and California. On the near side of Ford Island, to the left, are light cruisers Detroit and Raleigh, target and training ship Utah and seaplane tender Tangier. Raleigh and Utah have been torpedoed, and Utah is listing sharply to port. Japanese planes are visible in the right center (over Ford Island) and over the Navy Yard at right. U.S. Navy planes on the seaplane ramp are on fire. Japanese writing in the lower right states that the photograph was reproduced by authorization of the Navy Ministry.

Attack on Pearl Harbor: Photograph of Battleship Row taken from a Japanese plane at the beginning of the attack. The explosion in the center is a torpedo strike on USS West Virginia. Two attacking Japanese planes can be seen: one over USS Neosho and one over the Naval Yard.

Background

War between Japan and the U.S. was a possibility each nation had been planning for since the 1920s, and serious tensions began with Japan’s 1931 invasion of Manchuria. Over the next decade, Japan continued to expand into China, leading to all-out war between those countries in 1937. Japan spent considerable effort trying to isolate China and achieve sufficient resource independence to attain victory on the mainland; the “Southern Operation” was designed to assist these efforts.

From December 1937, events such as the Japanese attack on USS Panay, the Allison incident, and the Nanking Massacre swung public opinion in the West sharply against Japan. Fearing Japanese expansion, the U.S., the United Kingdom, and France provided loan assistance for war supply contracts to the Republic of China.

The U.S. ceased oil exports to Japan in July 1941 following Japanese expansion into French Indochina after the fall of France, in part because of new American restrictions on domestic oil consumption. This caused the Japanese to proceed with plans to take the Dutch East Indies, an oil-rich territory. On August 17, Roosevelt warned Japan that the U.S. was prepared to take steps against Japan if it attacked “neighboring countries.” The Japanese were faced with the option of either withdrawing from China and losing face or seizing and securing new sources of raw materials in the resource-rich, European-controlled colonies of Southeast Asia.

The Japanese attack had several major aims. First, it intended to destroy important American fleet units, thereby preventing the Pacific Fleet from interfering with Japanese conquest of the Dutch East Indies and Malaya and enabling Japan to conquer Southeast Asia without interference. Second, it was hoped to buy time for Japan to consolidate its position and increase its naval strength before shipbuilding authorized by the 1940 Vinson-Walsh Act erased any chance of victory. Third, to deliver a blow to America’s ability to mobilize its forces in the Pacific, battleships were chosen as the main targets since they were the prestige ships of any navy at the time. Finally, it was hoped that the attack would undermine American morale so the U.S. government would drop its demands contrary to Japanese interests and seek a compromise peace.

Aftermath of the Attack

The day after the attack, Roosevelt delivered his famous Infamy Speech to a Joint Session of Congress, calling for a formal declaration of war on the Empire of Japan. Congress obliged his request less than an hour later. On December 11, Germany and Italy, honoring their commitments under the Tripartite Pact, declared war on the United States. The pact was an earlier agreement between Germany, Italy, and Japan, which had the principal objective of limiting U.S. intervention in any conflicts involving the three nations. Congress issued a declaration of war against Germany and Italy later that same day. The UK actually declared war on Japan nine hours before the U.S. did, partially due to Japanese attacks on Malaya, Singapore, and Hong Kong and partially due to Winston Churchill’s promise to declare war “within the hour” of a Japanese attack on the United States.

The attack was an initial shock to all the Allies in the Pacific Theater. Further losses compounded the alarming setback. Japan attacked the Philippines hours later. Only three days after the attack on Pearl Harbor, the battleships Prince of Wales and Repulse were sunk off the coast of Malaya, causing British Prime Minister Winston Churchill later to recollect,

“In all the war I never received a more direct shock. As I turned and twisted in bed the full horror of the news sank in upon me. There were no British or American capital ships in the Indian Ocean or the Pacific except the American survivors of Pearl Harbor who were hastening back to California. Over this vast expanse of waters Japan was supreme and we everywhere were weak and naked.”

The Battle of Midway

The Battle of Midway was a decisive naval battle in the Pacific Theater of World War II, won by the American navy after code-breakers discovered the date and time of the Japanese attack.

Learning Objectives

Describe the events of the Battle of Midway

Key Takeaways

Key Points

  • This Japanese operation, like the earlier attack on Pearl Harbor, sought to eliminate the United States as a strategic power in the Pacific, giving Japan a free hand in establishing supremacy in East Asia.
  • American cryptographers were able to determine the date and location of the planned attack, enabling the forewarned U.S. Navy to prepare its own ambush.
  • All four of Japan’s large aircraft carriers and a heavy cruiser were sunk, while the U.S. lost only the carrier Yorktown and a destroyer.
  • After Midway and the exhausting attrition of the Solomon Islands campaign, Japan’s capacity to replace its losses in material and men rapidly became insufficient to cope with mounting casualties, while the United States’ massive industrial and training capabilities made losses far easier to replace. Thus, the Midway battle was a turning point in the war.

Key Terms

  • Pacific Theater: A major theater of the war between the Allies and Japan. It was defined by the Allied powers’ Pacific Ocean Area command, which included most of the Pacific Ocean and its islands and excluded mainland Asia, the Philippines, the Dutch East Indies, Borneo, Australia, most of the Territory of New Guinea, and the western part of the Solomon Islands.
  • Greater East Asia Co-Prosperity Sphere: An imperialist propaganda concept created and promulgated for occupied Asian populations during the first third of the Shōwa era by the government and military of the Empire of Japan. It extended further than East Asia and promoted the cultural and economic unity of Northeast Asians, Southeast Asians, and Oceanians. It also declared the intention to create a self-sufficient “bloc of Asian nations led by the Japanese and free of Western powers.”

The Battle of Midway was a decisive naval battle in the Pacific Theater of World War II. Between June 4 and 7, 1942, only six months after Japan’s attack on Pearl Harbor and one month after the Battle of the Coral Sea, the United States Navy under Admirals Chester Nimitz, Frank Jack Fletcher, and Raymond A. Spruance decisively defeated an attacking fleet of the Imperial Japanese Navy under Admirals Isoroku Yamamoto, Chuichi Nagumo, and Nobutake Kondo near Midway Atoll, inflicting devastating damage on the Japanese fleet that proved irreparable. Military historian John Keegan called it “the most stunning and decisive blow in the history of naval warfare.”

Reasons for the Attack

The Japanese operation, like the earlier attack on Pearl Harbor, sought to eliminate the United States as a strategic power in the Pacific, 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 and thus ensure Japanese dominance in the Pacific. 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 preparatory for further attacks against Fiji, Samoa, and Hawaii itself.

The plan was handicapped by faulty Japanese assumptions of the American reaction and poor initial dispositions. Most significantly, American cryptographers were able to determine the date and location of the planned attack, enabling the forewarned U.S. Navy to prepare its own ambush. All four of Japan’s large aircraft carriers—Akagi, Kaga, Soryu and Hiryu, part of the six-carrier force that attacked Pearl Harbor six months earlier—and a heavy cruiser were sunk, while the U.S. lost only the carrier Yorktown and a destroyer. After Midway and the exhausting attrition of the Solomon Islands campaign, Japan’s capacity to replace its losses in material (particularly aircraft carriers) and men (especially well-trained pilots and maintenance crewmen) rapidly became insufficient to cope with mounting casualties, while the United States’ massive industrial and training capabilities made losses far easier to replace. The Battle of Midway, along with the Guadalcanal Campaign, is considered a turning point in the Pacific War.

USS Yorktown ship just hit by torpedo fire, surrounded by smoke.

USS Yorktown: Yorktown at the moment of impact of a torpedo from a Nakajima B5N of Lieutenant Hashimoto’s 2nd fleet.

The Role of Code-Breaking

American Admiral Chester Nimitz had one priceless advantage going into battle: US cryptanalysts had partially broken the Japanese Navy’s JN-25b code. Since early 1942, the US had been decoding messages stating that there would soon be an operation at objective “AF”. It was initially not known where “AF” was, but Commander Joseph Rochefort and his team at Station HYPO were able to confirm that it was Midway; Captain Wilfred Holmes devised a ruse of telling the base at Midway (by secure undersea cable) to broadcast an uncoded radio message stating that Midway’s water purification system had broken down. Within 24 hours, the code breakers picked up a Japanese message that “AF was short on water.” No Japanese radio operators who intercepted the message seemed concerned that the Americans were broadcasting uncoded that a major naval installation close to the Japanese threat ring was having a water shortage, which could have tipped off Japanese intelligence officers that it was a deliberate attempt at deception. HYPO was also able to determine the date of the attack as either June 4 or 5 and provide Nimitz with a complete IJN order of battle. Japan had a new codebook, but its introduction was delayed, enabling HYPO to read messages for several crucial days. The new code came into use on May 24 and took several days to crack, but the important breaks had already been made.

As a result, the Americans entered the battle with a very good picture of where, when, and in what strength the Japanese would appear. Nimitz knew that the Japanese had negated their numerical advantage by dividing their ships into four separate task groups, all too widely separated to support each other. This dispersal resulted in few fast ships being available to escort the Carrier Striking Force, reducing the number of anti-aircraft guns protecting the carriers. Nimitz calculated that the aircraft on his three carriers plus those on Midway Island gave the U.S. rough parity with Yamamoto’s four carriers, mainly because American carrier air groups were larger than Japanese ones. The Japanese, by contrast, remained mainly unaware of their opponent’s true strength and dispositions even after the battle began.

The Battle

As anticipated by Nimitz, the Japanese fleet arrived off Midway on June 4 and was spotted by PBY patrol aircraft. Nagumo executed a first strike against Midway, while Fletcher launched his aircraft for Nagumo’s carriers. At 09:20 the first U.S. carrier aircraft arrived, TBD Devastator torpedo bombers from Hornet, but their attacks were poorly coordinated and ineffectual; thanks in part to faulty aerial torpedoes, they failed to score a single hit and all 15 were wiped out by defending Zero fighters. At 09:35, 15 additional TBDs from Enterprise attacked and 14 were lost, again with no hits. Thus far, Fletcher’s attacks were disorganized and seemingly ineffectual, but succeeded in drawing Nagumo’s defensive fighters down to sea level where they expended much of their fuel and ammunition repulsing the two waves of torpedo bombers. As a result, when U.S. dive bombers arrived at high altitude, the Zeros were poorly positioned to defend. To make matters worse, Nagumo’s four carriers drifted out of formation in their efforts to avoid torpedoes, reducing the concentration of their anti-aircraft fire. Nagumo’s indecision had also created confusion aboard his carriers. Alerted to the need of a second strike on Midway but wary of the need to deal with the American carriers that he now knew were in the vicinity, Nagumo twice changed the arming orders for his aircraft. As a result, the American dive bombers found the Japanese carriers with their decks cluttered with munitions as the crews worked hastily to properly re-arm their air groups.

With the Japanese CAP out of position and the carriers at their most vulnerable, SBD Dauntlesses from Enterprise and Yorktown appeared at an altitude of 10,000 feet (3,000 m) and commenced their attack, quickly dealing fatal blows to three fleet carriers: Sōryū, Kaga, and Akagi. Within minutes, all three were ablaze and had to be abandoned with great loss of life. Hiryū managed to survive the wave of dive bombers and launched a counter-attack against the American carriers, which caused severe damage to Yorktown (later finished off by a Japanese submarine). A second attack from the U.S. carriers a few hours later found and destroyed Hiryū, the last remaining fleet carrier available to Nagumo.

With his carriers lost and the Americans withdrawn out of range of his powerful battleships, Yamamoto was forced to call off the operation, leaving Midway in American hands. The battle proved to be a decisive victory for the Allies. For the second time, Japanese expansion had been checked and its formidable Combined Fleet was significantly weakened by the loss of four fleet carriers and many highly trained, virtually irreplaceable personnel. Japan would be largely on the defensive for the rest of the war.

The Guadalcanal Campaign

Guadalcanal marked the decisive Allied transition from defensive operations to the strategic initiative in the Pacific theater, leading to offensive operations such as the Solomon Islands, New Guinea, and Central Pacific campaigns that eventually resulted in Japan’s surrender and the end of World War II.

Learning Objectives

Understand the strategic significance of the Guadalcanal Campaign

Key Takeaways

Key Points

  • Up to this point, the Allies were on the defensive in the Pacific, but the strategic victories at Midway and other battles provided an opportunity to seize the initiative from Japan.
  • On August 7, 1942, Allied forces, predominantly United States Marines, 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 Allied supply and communication routes between the U.S., Australia, and New Zealand.
  • 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.
  • Surprised by the Allied offensive, the Japanese made several attempts between August and November to retake Henderson Field.
  • Three major land battles, seven large naval battles (five nighttime surface actions and two carrier battles), and continual, almost daily aerial battles culminated in the decisive Naval Battle of Guadalcanal in early November, in which the last Japanese attempt to bombard Henderson Field from the sea and land with enough troops to retake it was defeated.

Key Terms

  • parity: Functional equivalence, as in the weaponry or military strength of adversaries.
  • Europe first: Also known as Germany first, the key element of the grand strategy agreed upon by the United States and the United Kingdom during World War II. According to this policy, the United States and the United Kingdom would use the preponderance of their resources to subdue Nazi Germany in Europe first. Simultaneously, they would fight a holding action against Japan in the Pacific, using fewer resources. After the defeat of Germany—considered the greatest threat to Great Britain—all Allied forces could be concentrated against Japan.

The Guadalcanal Campaign, also known as the Battle of Guadalcanal and code-named Operation Watchtower, originally referred to an operation to take the island of Tulagi by Allied forces. This military campaign was 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.

Overview

On August 7, 1942, Allied forces, predominantly United States Marines, 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 Allied 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 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 American and Australian naval forces supported the landings.

Surprised by the Allied offensive, the Japanese made several attempts between August and November to retake Henderson Field. Three major land battles, seven large naval battles (five nighttime surface actions and two carrier battles), and continual, almost daily aerial battles culminated in the decisive Naval Battle of Guadalcanal in early November, in which the last Japanese attempt to bombard Henderson Field from the sea and land with enough troops to retake it was defeated. In December, the Japanese abandoned their 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.

The Guadalcanal campaign was a significant strategic combined arms Allied victory in the Pacific theater. Along with the Battle of Midway, it has been called a turning-point in the war against Japan. The Japanese reached the peak of their conquests in the Pacific. The victories at Milne Bay, Buna-Gona, and Guadalcanal marked the Allied transition from defensive operations to strategic initiative, leading to offensive operations such as the Solomon Islands, New Guinea, and Central Pacific campaigns that eventually resulted in Japan’s surrender and the end of World War II.

Background

On December 7, 1941, Japanese forces attacked the United States Pacific Fleet at Pearl Harbor, Hawaii. The attack crippled much of the U.S. battleship fleet and precipitated an open and formal war between the two nations. The initial goals of Japanese leaders were to neutralize the U.S. 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.

Two attempts by the Japanese to continue their strategic initiative and offensively extend their outer defensive perimeter in the south and central Pacific to where they could threaten Australia and Hawaii or the U.S. West Coast were thwarted at the naval battles of Coral Sea and Midway respectively. Coral Sea was a tactical stalemate, but a strategic Allied victory which became clear only much later. Midway was not only the Allies’ first major victory against the Japanese, it significantly reduced the offensive capability of Japan’s carrier forces but did not change their offensive mindset for several crucial months in which they compounded mistakes by moving ahead with brash decisions such as the attempt to assault Port Moresby over the Kokoda trail. Up to this point, the Allies were on the defensive in the Pacific, but these strategic victories provided them an opportunity to seize the initiative from Japan.

Significance

The Battle of Guadalcanal was one of the first prolonged campaigns in the Pacific, alongside the related and concurrent Solomon Islands campaign. Both were battles that strained the logistical capabilities of the combatant nations. For the United States, this need prompted the development of effective combat air transport for the first time. A failure to achieve air superiority forced Japan to rely on reinforcement by barges, destroyers, and submarines, with very uneven results. Early in the campaign, the Americans were hindered by a lack of resources as they suffered heavy losses in cruisers and carriers, with replacements from ramped-up shipbuilding programs still months away.

The U.S. Navy suffered such high personnel losses during the campaign that it refused to publicly release total casualty figures for years. However, as the campaign continued and the American public became more and more aware of the plight and perceived heroism of the American forces on Guadalcanal, more forces were dispatched to the area. This spelled trouble for Japan as its military-industrial complex was unable to match the output of American industry and manpower. As the campaign wore on, the Japanese were losing irreplaceable units while the Americans were rapidly replacing and even augmenting their forces.

The Guadalcanal campaign was costly to Japan both strategically and in material losses and manpower. Roughly 30,000 personnel, including 25,000 experienced ground troops, died during the campaign. As many as three-quarters of the deaths were from non-combat causes such as starvation and tropical diseases. The drain on resources directly contributed to Japan’s failure to achieve its objectives in the New Guinea campaign.

After the victory at the Battle of Midway, America was able to establish naval parity in the Pacific. However, this alone did not change the direction of the war. It was only after the Allied victories in Guadalcanal and New Guinea that the Japanese offensive thrust was ended and the strategic initiative passed to the Allies permanently. The Guadalcanal Campaign ended all Japanese expansion attempts and placed the Allies in a position of clear supremacy. It can be argued that this Allied victory was the first step in a long string of successes that eventually led to the surrender of Japan and the occupation of the Japanese home islands.

The “Europe first” policy of the United States initially only allowed for defensive actions against Japanese expansion to focus resources on defeating Germany. However, Admiral King’s argument for the Guadalcanal invasion and its successful implementation convinced President Franklin D. Roosevelt that the Pacific Theater could be pursued offensively as well. By the end of 1942, it was clear that Japan had lost the Guadalcanal campaign, a serious blow to Japan’s strategic plans for defense of its empire and an unanticipated defeat at the hands of the Americans.

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 they had previously. In addition, the Allies viewed the eventual outcome of the Pacific War with increased optimism.

Photo of American soldiers walking through water with palm trees and other plants in the background.

Guadalcanal Campaign: A U.S. Marine patrol crosses the Matanikau River in September 1942.