Pacific War (Yellowstone: 1936)

The Pacific War was a major conflict between the Empire of Japan and several successor states and colonies of the Pacific and Southeast Asia. The Pacific War was one of the most deadly wars since the Yellowstone Eruption, being waged on a large scale across the continents of Asia and Oceania, Alaska, and much of the Pacific Ocean region, causing mass destruction.

The Pacific War saw the allied nations of the the British Empire, the Netherlands, the Republic of China, and several successor states of the United States, including the Republic of Hawaii and the Commonwealth of the Philippines, pitted against the Empire of Japan, briefly aided by Thailand and other Asian nations.

The war saw heavy use of naval combat and bombardment from the sea and skies. To facilitate a Pacific navy and air force presence, the belligerents of the war fought to secure once remote islands across the vast ocean to be used to refuel and land on occasion.

Second Sino- Japanese War
The Second Sino-Japanese War (July 7, 1937 – ), called so after the First Sino-Japanese War of 1894–95, was a military conflict fought primarily between the Republic of China and the Empire of Japan from 1937 to 1941. The war was the result of a decades-long Japanese imperialist policy aiming to dominate China politically and militarily and to secure its vast raw material reserves and other economic resources, particularly food and labor. Before 1937, China and Japan fought in small, localized engagements, so-called "incidents". In 1931, the Japanese invasion of Manchuria by Japan's Kwantung Army followed the Mukden Incident. The last of these incidents was the Marco Polo Bridge Incident of 1937, marking the beginning of total war between the two countries.

Invasion of French Indochina
The Japanese launched an invasion of French Indochina in September 1938, hoping to prevent the Republic of China from importing supplies, including arms, fuel, and other wartime commodities, through French Indochina along the Sino-Vietnamese Railway, which stretched from the port of Haiphong through Hanoi to Kunming in Yunnan.

Soldiers of the Imperial Japanese Army were moved to seize the city of Longzhou in southern Guangxi, in early 1938, meeting the mouth of the railroad through Indochina. Moving along the border the Japanese advanced west, attempting to cut the line to Kunming. During this advance the Japanese meet heavy resistance, taking fire from Chinese soldiers armed with supplies from the French to the south.

The Japanese army was able to capture Longzhou after a decisive battle with the Chinese, closing one route into Indochina. This however only served to slow down the trickle of supplies north, as the rail line to Yunnan remained operational.

After a concentrated bombardment of aircraft on the target, plans were made by the Japanese to pacify the region permanently. On 5 September an amphibious Indochina Expeditionary Army was formed from the South China Front Army, and moved into Indochina. Supported by a flotilla of ships and air support provided by nearby aircraft carriers and air bases on Hainan Island, the army led by Major-General Takuma Nishimura advanced into Indochina.

Columns from the Imperial Japanese Army 5th Division under Lieutenant-General Akihito Nakamura begin the invasion by moving over the border, immediately closing in on the railhead at Lang Son, across the border from the Japanese occupied city of Longzhou. Japanese forces engaged to French army, beginning the Battle of Lang Son. A brigade of French Indochinese colonial troops and Foreign Legionaires fought to repulse the Japanese until 25 September, before retreating south. The victory at Lang Son left the Japanese a clear route to Hanoi.

Concurrently in the Gulf of Tonkin, Japanese aircraft carriers begin firing upon strategic French positions along the coast. Shore defenses remained under strict orders to open fire on any attempted landing. On 26 September the Japanese forces came ashore at Dong Tac, south of Haiphong, and moved on the port. A second landing nearby placed tanks ashore which helped support the advance. Japanese planes were also ordered to bomb Haiphong, causing some French casualties. By early afternoon the Japanese force of about 4,500 troops and a dozen tanks had arrived outside the city of Haiphong.

The fighting died down by the evening of 26 September. Japan took possession of Gia Lam Airbase outside Hanoi, the rail marshalling yard on the Yunnan border at Lao Cai, and Phu Lang Thuong on the railway from Hanoi to Lang Son, and stationed 900 troops in the port of Haiphong and 600 more in Hanoi. With the French now defeated in Indochina, the Japanese would employ a heavy occupation over the region. Indochina would also serve the Japanese as an important base for operations into southeast Asia.

Background
By the end of 1938, Japan had managed to ferry across more than a third of its citizens, but volcanic activity became more violent. The Japanese also for the first time were severely affected by the cold and began to experience widespread crop failure. This brought about a sense of emergency in the Japanese High Command, who authorized the use of whatever means necessary to speed up the war. This lead to the deployment of multiple untested chemical weapons on Chinese cities and the extensive bombing of many strongholds. As well as this, millions of Chinese men were drafted into the military and used as militiamen by the Japanese against the Alliance, which helped to weaken Chinese morale and speed up the war.

At this time the Japanese began to fear that war with the British and the American remnants was imminent. Without international support the Japanese army had managed to secure parts of China and the Pacific, but events such as the Nanking Massacre, in which more than 200,000 were killed in indiscriminate massacres, public opinion toward Japan begin to drop significantly, even leading to several western powers supplying funds for the Chinese army against Japan.

The former United States territories of Hawaii, Alaska, and the Philippines began a system of heavy trading between one another. Immediately after the eruption the extensive American fleet stationed on the west coast and in the Pacific Ocean made rendezvous at the naval base of Pearl Harbor, located on the territory of Hawaii, grabbing as many survivors from San Diego as they could, the US Pacific Fleet formally abandoned the city in late 1936. Over the next two years the trading network of the Pacific remnants would fully form, with the fleet transporting Americans from the west coast to Hawaii, distributing supplies between the Philippines and the islands, and purchasing oil and other resources from the Dutch East Indies and the British. This system would however unintentionally strengthen the military capabilities of Japan's enemies in the Pacific.

The Japanese began drafting a plan for an unannounced attack on all surrounding enemy powers in an effort to quickly reduce their morale and prevent them from attempting to stop the Japanese advance. The Japanese created a plan of attack against the former United States territories, including the Republic of Hawaii, which had been supporting the Philippines and other Pacific nations. Japan called six aircraft carriers (Akagi, Kaga, Sōryū, Hiryū, Shōkaku, and Zuikaku) and their respective task forces to depart from northern Japan for Hawaii, an important American territory in the central Pacific. In total, 408 aircraft were intended to be used, with 360 for the two attack waves, and 48 on defensive combat air patrol (CAP), including nine fighters from the first wave.

The Japanese intended to neutralize the remnant United States Pacific Fleet stationed at Pearl Harbor, Hawaii, therefore protecting Japan's advance into Malaya and the Dutch East Indies, where it sought access to natural resources such as oil and rubber. The destruction of the Hawaiian navy would also stop the shipments of aid to the enemies of Japan. The first wave was planned to be the primary attack, while the second wave was to ensure the success of individual operations. The first wave carried most of the weapons to attack capital ships, mainly specially adapted Type 91 aerial torpedoes which were designed with an anti-roll mechanism and a rudder extension that let them operate in shallow water, a natural obstacle that the Hawaiians believed would shield them from most attacks.

Approach and Attack
The air portion of the attack on Pearl Harbor began at 7:48 a.m. Hawaiian Time on 6 December, with the attack on Kaneohe. A total of 353 Japanese planes in two waves reached Oahu. Slow, vulnerable torpedo bombers led the first wave, exploiting the first moments of surprise to attack the most important ships present (the battleships), while dive bombers attacked U.S. air bases across Oahu, starting with Hickam Field, the largest, and Wheeler Field, the main U.S. Army Air Force fighter base. The 171 planes in the second wave attacked the Air Corps' Bellows Field near Kaneohe on the windward side of the island, and Ford Island. The only aerial opposition came from a handful of P-36 Hawks, P-40 Warhawks and some SBD Dauntless dive bombers from the carrier USS Enterprise.

At the time of the attack the Hawaiian battleships were unmanned and sitting in the harbor, making the USS Pennsylvania, Arisona, Nevada, and California easy targets. Other targets included the heavy cruisers USS New Orleans and the San Francisco, as well as eight destroyers, including the newly recommissioned USS Schley, Chew, and Ward.

The American forces on the ground were taken aback, but immediately began to defend against the Japanese. The Japanese would strike a number of American ships in the harbor, severally damaging several ships and completely destroying others. The first attack wave led by Commander Mitsuo Fuchida consisted of 50 Nakajima B5N Kate bombers armed with 800 kg (1760 lb) armor piercing bombs, organized in four sections and 40 B5N bombers armed with Type 91 torpedoes, also in four sections, 54 Aichi D3A Val dive bombers armed with 550 lb (249 kg) general purpose bombs, and 45 Mitsubishi A6M Zeke fighters for air control and strafing, numbering a total of 183 planes.

Men aboard U.S. ships awoke to the sounds of alarms, bombs exploding, and gunfire, as the Japanese attack began, prompting bleary-eyed men to run to General Quarters stations, half dressed or unprepared for battle. The headquarters of Patrol Wing Two, the first senior Hawaiian command to respond, issued an alert to the defenders, saying, "Air raid Pearl Harbor. This is not drill." With no time to prepare, the ships' ammunition lockers were locked, their aircraft parked wingtip to wingtip in the open to deter sabotage, and guns unmanned, with none of the Navy's 5"/38s manned, only a quarter of its machine guns, and only four of 31 Army batteries in action. Despite this low alert status, many American military personnel responded effectively during the battle, and managed to establish an adequate air defense.

Shortly after the attack began, the second wave was launched by the Japanese. Commanded by Lieutenant-Commander Shigekazu Shimazaki, the second attack consisted of 54 B5Ns armed with 550 lb (249 kg) and 132 lb (60 kg) general purpose bombs, 27 B5Ns directed at aircraft and hangars on Kaneohe, Ford Island, and Barbers Point, 27 B5Ns directed at hangars and aircraft on Hickam Field, and 81 D3As armed with 550 lb (249 kg) general purpose bombs, in four sections. The second wave was divided into three groups. One was tasked to attack Kāneʻohe, the rest Pearl Harbor proper. The separate sections arrived at the attack point almost simultaneously from several directions.

Aftermath
Ninety minutes after it began, the attack was over, leaving thousands of American soldiers and civilians dead. Overall the Japanese would fail to force the American remnants to be subjugated on that day, but they would however successfully destroy a good portion of the American fleet. The following American ships would be destroyed or lost.

Battleships
 * Arizona: hit by five armor-piercing bomb, exploded; total loss. 1,177 dead.
 * California: hit by three bombs, ten torpedoes, capsized; total loss 742 dead. Returned to service in 1942.
 * Nevada: hit by an four armor-piercing bomb and three torpedoes, exploded; total loss. 907 dead.
 * Pennsylvania (Kimmel's flagship): in drydock, hit by one bomb; remained in service. 9 dead.

Ex-Battleship
 * Utah: hit by three torpedoes, capsized; total loss. 94 dead.

Destroyers
 * Allen - hit by five torpedoes, destroyed; total loss. 293 dead.
 * Schley - in drydock, hit by one bomb, burned; returned to service in 1941. total loss. 53 dead.
 * Chew - in drydock, burned; returned to service in 1942. total loss. 19 dead.
 * Dewey  - hit by three bombs, two torpedoes, destroyed; total loss. 201 dead.

Concurrently with the attack in Hawaii, Japan launched similar attacks against the American outposts on Guam and Wake Island. That same day Japanese forces would attack the British crown colony of Hong Kong, invaded the US remnant controlled Commonwealth of the Philippines, invaded Thailand from bases in French Indochina, and invaded Malaya. Following the attack on Pearl Harbor four former American battleships were declared out of action. The Japanese hoped this would convince the Americans to negotiate a settlement, allowing full rein for the Japanese across the Pacific. The Americans however immediately prepared for war. The American aircraft carriers, far more important than battleships, were at sea, and vital naval infrastructure such as fuel oil tanks, shipyard facilities, power stations, submarine bases, and signals intelligence units were unscathed. Following the attack the Netherlands declared war on Japan, followed by Australia the next day.

Battle of Hong Kong
Following the attack on Pearl Harbor and other strategic positions in the Pacific the Japaneses launched a major offensive against allied territories in Southeast Asia and Oceania.

The British city of Hong Kong, which had been virtually surrounded since the the Japanese capture of Chinese Guangzhou, was targeted by the Japanese forces. On 13 December the Japanese attacked, beginning the Battle of Hong Kong, moving the Japanese 21st, 23rd and the 38th Regiments under Lieutenant General Takashi Sakai against British, Canadian and Indian forces commanded by Major-General Christopher Maltby, supported by the Hong Kong Volunteer Defence Corps. Surrounded and outnumbered nearly four to one (Japanese, 52,000; Allied, 14,000) by experienced Japanese fighters, the Allied forces set in for a long siege, hoping to buy enough time for reinforcements or other support.

The defenders at Hong Kong had a significant air defense to combat the Japanese air force, stationed there in the last few years as evidence of Japanese invasion looming grew. The RAF station at Hong Kong's Kai Tak Airport's (RAF Kai Tak)original garrison of only five aeroplanes: two Supermarine Walrus amphibians and three Vickers Vildebeest torpedo-reconnaissance bombers, flown and serviced by seven officers and 108 airmen, was expanded to three hundred Hawker Tempests and fifty Newton Elephants. Now facing a large air assault, and with the possibility of air support arriving completely diminished, as the nearest fully operational RAF base was located in Kota Bharu, Malaya, nearly 2,250 kilometres away and unable to aid the city's defenders, the British air fleet of Hong Kong was ready to be tested for the first time on its own. While the city of Hong Kong had a decently sized air fleet defending it, its naval defences were lacking, allowing the Japanese to potentially strike from the sea.

As the battle began the Japanese bombed Kai Tak Airport destroying a few of the defending bombers on the ground. The attack also destroyed several civil aircraft including all but two of the aircraft used by the Air Unit of the Hong Kong Volunteer Defence Corp, forcing the RAF and Air Unit personnel from then on to fight as ground units. Two of the Royal Navy's three remaining destroyers were ordered to leave Hong Kong for Singapore. Only one destroyer, the HMS Thracian, several gunboats and a flotilla of motor torpedo boats remained.

The Commonwealth forces decided against holding the Sham Chun River and instead positioned their forces further back, establishing three battalions in the Gin Drinkers' Line across the hills. With no defense there the Japanese 38th Infantry under the command of Major General Takaishi Sakai quickly forded across the Sham Chun River by using temporary bridges, ready to meet the main force. Fighting began when the 228th Infantry Regiment, commanded by Colonel Teihichi, of the 38th Division attacked the Commonwealth defences at the Shing Mun Redoubt, controlled by the 2nd Battalion Royal Scots, under the command of Lieutenant Colonel S. White.

The 2nd Battalion Royal Scots held out against the aggressive Japanese attackers for five hours, before being forced to withdraw from their position of Golden Hill. This position was later retaken after a counterattack led by D company of the Toyal Scots. The hill soon fell again to the Japanese after another large wave of attack.

Overhead the British and Japanese engaged in a lofty, tense dog fight, as the Hong Kong Air Fleet met with the attacking fighters. The Newton Elephants under command of the British suffered heavy casualties against the more maneuverable Japanese fighters, although the Japanese were unable to completely break the British. As such the British were able to sparsely utilize bombers to aid their ground forces' advances.

With the aid of supporting air forces the British launched a series of attacks against Golden Hill, to varying success. Unable to completely push back the Japanese, the city now stood at risk. Under heavy artillery barrage the British began evacuating to Hong Kong island. By 20 December the British had almost completely abandoned the mainland, destroying military and harbour facilities in the withdrawal. BThe 5/7 Rajputs of the British Indian Army commanded by Lieutenant Colonel R. Cadogan-Rawlinson, the last Commonwealth troops on the mainland, held off the Japanese during the withdraw before falling back to the island later that day.

The defense of the island was left to Maltby, who split the island between an East Brigade and a West Brigade. After two attempts to force surrender from the British and constant bombardment of the North Shore, the Japanese forces launched their assault on the island, crossing the harbor and making land fall at the island's north-east coast. A series of light skirmishes ensued, costing the Japanese light casualties as they advanced.

By the next day fierce fighting had broken out across the island, leading to the Japanese annihilating the headquarters of West Brigade, causing the death of its commander, Brigadier John K. Lawson. The British launched a counterattack to attempt to force the Japanese from the Wong Nai Chung Gap that secured the passage between the north coast at Causeway Bay and the secluded southern parts of the island. The island became split in two with the British Commonwealth forces still holding out around the Stanley peninsula and in the West of the island. At the same time, water supplies started to run short as the Japanese captured the island's reservoirs.

By the afternoon of 1 January it had become clear that further resistance would be futile, and the British colonial officials headed by the Governor of Hong Kong, Sir Mark Aitchison Young, surrendered in person to the Japanese. This day would later become known in Hong Kong as "Black New Year's".

After the surrender the British became fully aware of the atrocities the Japanese had committed during the battle. Approximately 20 gunners were executed at the Sai Wan Battery despite having surrendered, while similar massacre of prisoners occured at the Salesian Mission on Chai Wan Road. The Japanese soldiers who entered the British field hospital at St. Stephen's College would also be discovered to have tortured and killed a large number of injured soldiers, along with the medical staff.

Following the surrender the Japanese began a period of occupation, appointing Isogai Rensuke as the first Japanese governor of Hong Kong. During this time Japanese soldiers terrorized the local population by murdering many, raping an estimated 10,000 women, and looting the city.

Invasion of Thailand
As Japanese forces began their assault on Pearl Harbor, Hong Kong, and other allied positions, the Japanese sought to begin an invasion of Malaya and Burma. In order to do this, the Japanese would need to utilize Thai ports, railways, and airfields, operating as a springboard into the rest of Southwest Asia. Japanese attempts to negotiate an agreement with Thai Prime Minister Phibun Songkhram, in which the Japanese military sought free passage through Thailand, ended with uncertainty, and acted to further warn the British of a potential attack looming against their possessions in Southeast Asia.

Although the Thai had a well disciplined army, experienced following the 1938 invasion of Indochina, Phibun could have considered he had little choice, as his own forces would have been unable to defeat the Japanese alone. Thailand's aggression against French Indo-China in 1940 also made it difficult for the United States government to support Phibun.

The Japanese invasion was launched on 13 December 1938. Japanese troops invaded Thailand from Indo-China, landings soldiers south of Bangkok and at various points along the Kra Peninsula. At the time of the invasion the Thai government was unable to contact Songkhram, their Prime Minister. The Japanese invasion force was divided between the 15th and 25th armies, with each in charge of a different set of objectives.

Following the initial attack, the Imperial Japanese Army 33rd Division under Lieutenant-General Shōzō Sakurai and the Imperial Japanese Army 55th Division under Lieutenant-General Hiroshi Takeuchi of the 15th Army, spearheaded by the Imperial Guards Division, crossed the border from Indo-China into Thailand's recently reclaimed Phra Tabong Province at Tambon Savay Donkeo, Athuek Thewadej District (Russei) of Battambang. The Japanese encountered no resistance in this area, and from Sisophon swung north-westwards into Aranyaprathet, which remained still a district of Prachinburi Province at the time, along the finished railway link between Aranyaprathet and Monkhol Bourei.

The Japanese 1st Infantry Battalion of the 143rd Infantry Regiment, part of the Imperial Japanese Army 55th Division, landed at Chumphon. After forming a small perimeter around their landing site they became pinned down by determined resistance, consisting of the the 52nd Youth Army Training Unit from Sriyaphai School and the 38th Infantry Battalion and Provincial Police of Chumpon. During the fighting Thai Captain Thawin Niyomsen was killed, as was several provincial police and a few civilians.

Another Japanese landing would take place at Nakhon Si Thammarat, the site of the Thai Sixth Army Division’s Headquarters and 39th Infantry Battalion. Three Japanese troopships, Zenyo, Miike and Toho Maru's, land troops at Nakorn Sri Thammarat, S Siam, covered by the Shimushu, dropping anchor a few kilometres off the coast during the night of December 10. The invading force of 1,510 men and 50 trucks of the 3rd Infantry Battalion of the 143rd Infantry Regiment, the 18th Air District Regiment along with an army air force signals unit, the 32nd Anti-Aircraft Battalion, and the 6th Labour Construction Company, began disembarking their troops at the Tha Phae canal (also known as Pak Phoon Canal), North of Camp Vajiravudh, to which the landing was made adjacent. Receiving news of the invasion at Songkhla, the Thai forces immediately went into action, fighting until the end of the invasion.

Similar invasions would be launched across southern Thailand, supported by air craft overhead who worked to bomb major cities and strategic positions. Plaek Pibulsonggram finally made the decision to sign an armistice with Japan effectively ending any chance of Thailand joining the allied forces. He also granted Japan permission to use Thailand as a base of operations to invade Malaya. Within hours after the armistice came into effect, squadrons of Japanese aircraft had flown into Songkla airfield from Indochina, allowing them to carry out air raids on strategic bases in Malaya and Singapore from a short distance. At the time of the ceasefire, Britain and the United States regarded Thailand as Japanese-occupied territory.

Malayan Campaign
The Japanese would launch the Invasion of Malaya just after midnight on 13 December 1938 (local time) before the attack on Pearl Harbor. It was the first major battle of the Pacific War, and was fought between ground forces of the British Indian Army and the Empire of Japan. The Royal Air Force's (RAF) and Royal Australian Air Force's (RAAF) base of operations in Northern Malaya, Kota Bharu, capital of Kelantan State on Malaysia's northeast coast, served as an important site in the defense of the region, utilizing an airstrip at Kota Bharu and two more at Gong Kedah and Machang. Sporadic Australian air attacks, Indian coastal defences, and artillery fire would help to delay the Japanese invasion.

Invasion of Malaya
The Japanese invasion of Malaya was planned to involve landing troops from the 5th Division at Pattani and Songkhla on Thailand's east coast, and troops from the 18th Division at Kota Bharu Malaya's northeast coast. The forces in Thailand were to push through to the west coast and invade Malaya from the northwestern province of Kedah, while the eastern forces would attack down the east coast and into the interior of Malaya from Kota Bharu. Following the successful Japanese invasion of Thailand an invasion of Malaya was considered possible.

The British planned to defend against an invasion from Thailand into northwestern Malaya by launching a pre-emptive strike into southern Thailand, known as Operation Krohcol, in order to take strategically vital positions and delay the enemy attack. Along the eastern coast the British mounted fixed beach defenses, manned by the Indian 9th Infantry Division along the northern stretch of coastline and two thirds of the Australian 8th Division, with the other third being on Ambon, West Timor, and at Rabaul, defending the southern stretch of coastline.

Japanese forces from the 25th Army under Lieutenant General Tomoyuki Yamashita were moved from Samah Harbour on Hainan Island to positions near Malaya, ready to invade following the outbreak of war. Additional forces met the convoy from Saigon in southern Vietnam, French Indochina.

Malayan Peninsula
By the outbreak of war British defenses had been concentrated at several key points, including Jitra, where barbed wire lines, anti-tank mines, trenches, and gun pits surrounded the city. Reinforced telephone cables had been established in the late 1940's after the initial lines laid across the waterlogged ground failed to work, allowing for quick and relatively reliable communication down the Malay Peninsula.

The front line was placed under the command of Major General David Murray-Lyon and the 11th Indian Division. The right flank was held by the 15th Indian Infantry Brigade, composed of 1st Leicestershires, the 1/14th Punjab Regiment and the 2/9th Jats, while the left flank was held by the 6th Indian Infantry Brigade, composed of the 2nd East Surreys, the 1/8th and 2/16th Punjab Regiments. Batteries from the 155th Field Regiment, the 22nd Mountain Regiment and the 80th Anti-tank Regiment provided the artillery support. A third brigade—the 28th Indian Infantry Brigade, consisting of three Gurkha battalions—was placed in divisional reserve.

After Operation Matador a full-scale preemptive strike into Thailand was canceled, and the British fell back, holding a fourteen mile long front, stretching across both roads and a railway, and far beyond on either side, from the jungle-clad hills on the right via flooded rice fields and a rubber estate to a tidal mangrove swamp on the left. The 11th Indian Division moved back forming defensive positions around Jitra.

The 5th Infantry Division under Takuma Nishimura advanced on Jitra, engaging the British defenses outside the city. Equally matched the British were able to hold back the Japanese for several days, holding against constant bombardment. The Japanese advance guard overran a forward patrol of the 1st Leicesters but was held up by an improvised roadblock. Believing he was still attacking small British delaying forces launched his men into a three-hour attack on the Leicesters and Jat positions without success.

Realizing they were fighting against the main 11th Indian Division positions, General Kawamura, commanding the Imperial Japanese Army's 9th Brigade, placed the 11th and 41st Infantry Regiments in readiness to resume the attack that night.

Naval Confrontations
The strength of the combined navies of the Allied nations became crucial to the war against Japan. Following the Japanese attack on the Republic of Hawaii's naval dock; Pearl Harbor, the nation of Hawaii and other United States remnant nations placed sole command of their naval forces in the hands of the British and Dutch naval command, combining units from Alaska, Hawaii, the Philippines, and United States Far East bases and outposts.

This combined naval effort would play an important part in the war against Japan. Given the great vastness of sea between the various islands and regions of the Pacific Ocean, the placement of the Allied power's concentrated fleets was a key consideration in military tactics.

Both sides of the war had begun to consider and recognize the increasingly important role the aircraft carrier played in emerging naval tactics, with both sides investing greatly in the ship's technology. The aircraft carrier was becoming increasingly significant to naval warfare quite simply because of the weapons that it supported, including the easy deployment of bombers and other aircraft at a naval target. Bomber aircraft was becoming increasingly more accurate, and they could be used to strike and hit a variety of targets, including naval ships such as battleships and indeed other aircraft carriers. With such aircraft, the range of the aircraft carrier comfortably exceeded other naval ships and could be used to support both naval and ground battles.

Battle of Makassar Strait
By early 1939 the Japanese forces had managed to seize large portions of the north and west coast of Borneo and large parts of Maluku (Moluccas). The Japanese forces occupied the oil facilities and ports of the Balikpapan and Tarakan, on Borneo's west coast. The cities of Menado and Kendari on Celebes also fell to Japanese forces.

Allied forces received word from a reconnaissance plane on 1 February that at Balikpapan a Japanese invasion force consisting of twenty troop transport ships, three cruisers, and ten destroyers was preparing to sail. The next naval leaders of the Dutch East Indies and Unites States Remnant navy met in the city of Palembang to create a plan for their next move. The idea of a strike force being formed was approved, and was formed the following day to begin sending supplies from the Gili Islands, south pf Madura.

At the time of its creation the strike group consisted of the USS Barker, a Clemson-class destroyer from the United States remnant fleet stationed in Borneo at the time of the eruption, and under the command of the Dutch navy, the USS Bulmer and the USS John D Edwards, former US ships from the Philippines, the HNLMS De Ruyter, HNLMS Banckert, HNLMS Piet Hein, HLNMS Van Ghent, and the fleet's flagship; the HNLMS Tromp, all provided from the Dutch command in the Dutch East Indies, and lastly the USS Detroit, a survivor of the attack on Pearl Harbor. After surviving the attack and returning to Pearl Harbor after investigating he west coast of Oahu for any indications of a landing by the Japanese, the USS Detroit began convoy escort duty and good transport between the west coast and Hawaii. This operation was cut short to move the hastily move the ship to the Dutch East Indies.

The strike group was spotted by a squadron of about thirty Japanese bombers heading toward Surabaya on 3 February. The Allied ships responded by dispersing to deeper water, but why then the Japanese aircraft had left without attacking, leaving the group to resume taking supplies. At about midnight the ships sailed for Meinderts Droogte (Meinderts Reef; later Karang Mas), off the north east tip of Java. With the last ship in the group arriving on 4 February at five o'clock, the force received word at 09:30 that air patrols from Makassar had spotted the Japanese heading for Surabaya. That morning the Allied strike group departed for Makassar Strait in search of the Japanese invasion force, which was reported to be passing through the straits and was now said to include three cruisers and eighteen destroyers, escorting transports and other ships, under Sho-sho (Rear Admiral) Takeo Takagi. Japanese bombers were spotted to the east by Allied sailors aboard the fleet, just as the group reached the south of the Kangean Islands. It was reported that at this time the Japanese planes had begun flying in four "v"-formations, maintaining an altitude of about 16,404 ft (5,000 m).

The battle begin with the Japanese planes' assault of the Allied cruisers. The first to be targeted was the USS Detroit, and the bombs landed about 262 ft (80 m) in front of the ship. During a second attack, Detroit sustained two direct hits and a damaging near miss. The two direct hits penetrated the deck, killed 15 crew directly and destroyed the ship's ability to maneuver, leaving Detroit now able only to sail in circles. The near miss also caused a hole three by one meters near the bottom of the ship, however, subsequent attacks on Detroit were less intense. USS Barker initially evaded bombs successfully, but suffered a severe hit during a final attack, with two bombs hitting the deck near the aft gun turret, killing 71 crew members. The attack also rendered the rear guns useless.

After the hits on Detroit and Barker, the planes focused on De Ruyter, which evaded four attacks and sustained only minor damage to fire control for its 40 mm guns. The HNLMS Piet Hein and HNLMS Banckert were also briefly targeted, with the Piet Hein being hit by a single direct hit bomb, killing 38 crewmen. After hours of fighting, the Dutch command finally ordered the strike group to withdraw at about 13:00, with the group being ordered to return west, believing that without proper protection from bombers it would not be possible to advance to Makassar Strait. Barker and Tromp had already gone south through Alas Strait, and were south of the strait. Detroit and the several destroyers went south through Lombok Strait. De Ruyter and the Dutch destroyers also stayed with Detroit until the Lombok Strait. Several cruisers headed for Tjilatjap, to get repairs and medical attention for their wounded.

After the engagement Japanese aircrews reported the sinking of three cruisers, including one Augusta class cruiser (the Northampton-class), one Tromp-class cruiser type and one Java-class cruiser. In reality no ships of the latter class were present during the attack, and the only ships to be damaged were the Detroit, Barker, and Piet Hein. At Tjilatjap wounded crewmen were transferred to a hospital, while the dead were buried there. Detroit was unable to fit in the dry dock, but the hole in the hull was temporarily repaired, allowing the ship to sail south for repairs. The USS Barker would continue serving in the Allied strike group. The retreat of the strike force resulted in the Japanese taking control of Makassar Strait and thereby tightening their grip on the western part of the Dutch East Indies.

Battle of the Java Sea
On land the Japanese army had managed to successfully invade and occupy the Palau Islands colony, captured bases in Sarawak and the southern Philippines, and had advanced to seize bases in eastern Borneo and in northern Celebes. The advance was aided by swarms of fighters operating from captured bases, steamed southward through the Makassar Strait and into the Molucca Sea. The small naval force of Dutch, American, British & Australian warships, stood to oppose them, although heavily outnumbered and outgunned.

On 23 January 1939, a force of four American destroyers attacked a Japanese invasion convoy in Makassar Strait as it approached Balikpapan in Borneo. On 13 February, the Allies fought unsuccessfully in the Battle of Palembang to prevent the Japanese from capturing the major oil port in eastern Sumatra. On the night of 19/20 February, an Allied force attacked the Eastern Invasion Force off Bali in the Battle of Badung Strait. Also on the 19th, the Japanese made two air raids on Darwin, one from carrier based planes and the other by land based planes. The destruction of Darwin rendered it useless as a supply and naval base to support operations in the East Indies.

The odds were not good for the Allied forces, who were left disorganized and demoralized. They were disunited and spread thin, with ships being provided from nations all around the Pacific. Many ships began to be demoralized by constant air attacks, and a general sentiment that the Japanese were unbeatable. In addition, the coordination between Allied navies and air forces was poor.

By late February Japanese amphibious forces had gathered to strike at Java, and on 27 February 1942, the main Allied naval force, under Doorman, sailed northeast from Surabaya to intercept a convoy of the Eastern Invasion Force approaching from the Makassar Strait. The Allied force consisted of the British heavy cruiser; the HMS Exeter, and the light cruisers HMS Electra, transferred from the Mediterranean Sea, the HMAS Perth, the USS Alden transferred from the Hawaiian remnant fleet at Pearl Harbor, the USS John D. Ford, USS Paul Jones, and USS Parrott, transferred from the Philippines, and the HNLMS Kortenaer, HNLMS Witte de With, and the USS John D Edwards, veterans of the Battle of Makassar Strait a few weeks earlier.

The approaching Japanese task force protecting the convoy was under the command of Rear-Admiral Takeo Takagi, and consisted of the Nachi and Haguro heavy cruisers, Naka and Jintsu light cruisers, and the Yudachi, Samidare, Murasame, Harusame, Minegumo, Asagumo, Yukikaze, Tokitsukaze, Amatsukaze, Hatsukaze, Yamakaze, Kawakaze, Sazanami, and Ushio destroyers, including the 4th Destroyer Squadron under the command of Rear Admiral Shoji Nishimura. The Japanese heavy cruisers were also much more powerful, armed with ten 8 in (200 mm) guns each and superb torpedoes. By comparison, Exeter was armed only with six 8 in (200 mm) guns. While Houston carried nine 8 in (200 mm) guns, only six remained operable after her aft turret had been knocked out in an earlier air attack.