Imperial Japanese Army during the Pacific War
The Pacific War lasted from 1941-1945, with the Empire of Japan fighting against the United States and the British Empire. Most of the campaign was fought largely on a variety of small islands in the Pacific region. Compared to the European Theater, Pacific combat was brutal, marked by illness, disease, and ferocity. The Imperial Japanese Army typically fought alone in these engagements, often with very little naval or aerial support, and the IJA would quickly garner a reputation for their unrelenting spirit.
At the beginning of the Pacific War in 1941, the Imperial Japanese Army contained 51 divisions, 27 of which were stationed in China. A further 13 divisions defended the Manchurian-Soviet border, due to concerns about a possible attack by the Soviet Union. From 1942, troops were sent to Hong Kong, the Philippines, Thailand, Burma, Dutch East Indies, and Malaya. By 1945, there were 5.95 million men in the Imperial Japanese Army.
From 1943 onwards, Japanese troops suffered from a shortage of supplies, especially food, medicine, munitions, and armaments, largely due to submarine interdiction of supplies, and losses to Japanese shipping, which was worsened by a longstanding rivalry with the Imperial Japanese Navy. As many as two-thirds of Japan's total military deaths were a result of illness or starvation".
| Year | Regular army | Reservists | Total |
| 1941 | 1,032,500 | 992,500 | 2,025,000 |
| 1942 | 1,087,000 | 1,248,000 | 2,335,000 |
| 1943 | 1,502,000 | 2,295,000 | 3,797,000 |
| 1944 | 2,118,400 | 1,641,600 | 3,760,000 |
| 1945 | 2,444,000 | 3,506,000 | 5,950,000 |
Overarching goals
Japanese grand strategy was to expand its borders to help deal with Japan's lack of self-sufficiency, in particular, its lack of natural resources. Similar to the German concept of lebensraum, the Japanese perceived the conquest of Asia and Oceania as their right. After the Attack on Pearl Harbor in December 1941, the Empire of Japan was officially at war with the United States and the British Empire. Japan recognised that they would not be able to win a protracted war with the Allied Powers, and suggested that such operations should take no longer than 150 days. They were expecting that Germany would be able to force a British surrender, and subsequently, America would end the war on terms agreeable to Japanese interests.First offensive maneuvers (1941-1942)
Once the Pacific War began, the Imperial Japanese Army quickly captured many critical areas. These included British Malaya, Guam, the Philippines and Wake Island. A combination of Japanese naval supremacy and the Allied doctrine of 'Europe first' meant they saw relatively little opposition during this stage of the war. The Japanese control of a large part of Oceania and Asia gave them a strong initiative, as they were able to acquire many valuable resources, such as rubber and steel.tanks and trucks in Malaya, 1942.
Loss of momentum
The most significant loss for the Imperial Japanese Army was the Battle of Guadalcanal. The battle displayed that they could not continue to act on the offensive, and was the first major Allied victory on land. Guadalcanal would later be used as the point from which the United States Marines would attack the Palau Islands, Bougainville, and Guam. Vice Admiral Raizō Tanaka remarked "There is no question that Japan's doom was sealed with the closing of the struggle for Guadalcanal."After Guadalcanal, the Japanese were almost entirely on the defensive. Slowly, the American forces begin their island hopping campaign and a combination of unrestricted submarine warfare and air raids on Japan destroyed Japan's industrial capabilities, which they had very little defense against.
The island hopping campaign was very successful for the Allied forces, and though combat in the Pacific was gruelling, each individual island had remarkably few men on it to engage the enemy, usually less than a single division, and the Allies had very little problem establishing naval and aerial supremacy. In the battles of Iwo Jima and Okinawa, the two islands closest to the Japanese mainland, the Imperial Japanese Army did inflict more casualties upon their enemy, and these battles were considerably lengthier than most others of the Pacific War, but they were still unable to prevent the American forces from taking the islands. The Battle of Peleliu had the highest casualty rate of any American amphibious invasion, at 40%, but likewise, they were still able to secure the island. An invasion of the Japanese mainland was planned, named Operation Downfall, the first stage of which would have been the invasion of Kyūshū island in November 1945, but after the Atomic bombings of Hiroshima and Nagasaki, Japan surrendered on the 2nd September, 1945, bringing the Second World War to a close. The end of the Pacific War would cost the American forces 426,000 casualties: 161,000 dead, 248,316 wounded, and 16,358 captured.
Equipment
The service rifle in the Imperial Japanese Army was the Type 38 rifle, a 5-round bolt-action rifle firing 6.5×50mmSR Arisaka, however, with the outbreak of the Second Sino-Japanese War, it was found to be lacking in power, and was replaced by the Type 99 rifle, which used the 7.7×58mm Arisaka, a round more comparable to those used by other countries, such as the.30-06 or.303 British, but both rifles were used until the end of the war., one of Imperial Japan's two service rifles during the war.
The most common machine guns used were the Type 96 light machine gun and Type 99 machine gun, firing the 6.5mm and 7.7mm respectively. They fired from 30-round magazines, loaded from the top, and though these weapons externally resemble the British Bren gun, and are sometimes believed to be copies, they are functionally and internally separate. Also used was the Type 92 Heavy Machine Gun, nicknamed 'The Woodpecker' for its sound, which fired from a 30-round 7.7mm feed tray. The lack of standardization harmed Japanese production efficiency, and can be considered a major contributing factor in the general absence of ammunition.
The only submachine gun in service in the Japanese Empire was the Type 100 submachine gun. It fired the sub-par 8x22mm Nambu round, and was modelled after the German MP-18. Only a few thousand were built, compared to the 1.75 million Thompsons, the SMG in use in the United States.
Compared to their American and British counterparts, Japanese small arms were largely inferior, though they had one weapon that their enemies did not, the Type 89 grenade discharger, better known as the knee mortar, a man-portable mortar, that could also be used in direct fire.
Japanese armor was also lacking. During the interwar period, Japan bought various Vickers 6-Tons, and largely modelled their own tank designs after them, but the effectiveness of such tanks was very limited. Though Japan was the first country to implement diesel engines, now commonplace, and the presences of domestic tanks at all put them above most of the world's armies, these tanks were considerably lacking in armor and firepower compared to their American counterparts - neither the light Type 95 Ha-Go nor the medium Type 97 Chi-Ha could penetrate an M4 Sherman.. The rather light armor of Japanese tanks also made them vulnerable against other means of attack, such as the M1 Bazooka.
Tactics
Though numerically, materially, and logistically, the cards appeared to be stacked against Japan, they were confident that they would emerge victorious, based upon their greater spirit compared to their enemies. Their tactical doctrine relied on unrelenting attack and surprise, to the extent that the word 'retreat' was de facto banned. Instead, it was a repositioning, or a transfer.In Japanese military culture, honor surmounted all else, which is why so exceptionally few Japanese soldiers willingly surrendered - during the Battle of Kwajalein, of the 5,000 Japanese men on the island, 4,300 were killed, and only 166 were captured. If a force was in danger of being overwhelmed, it would not be unusual for a commander to issue a banzai charge - all soldiers would charge directly at the enemy, the name coming from their battle cry, ""Tennōheika Banzai". Bayonets were standard issue for all Japanese rifles and light machine guns, and though psychologically powerful, most banzai charges ended in a one-sided slaughter of the Japanese forces.
Fanaticism and war crimes
Throughout the Second Sino-Japanese War and World War II, the Imperial Japanese Army had gained a reputation both for its fanaticism and for its brutality against prisoners of war and civilians alike – with the Nanking Massacre being the most well known example. After Japan surrendered in the summer of 1945, many Imperial Japanese Army officers and enlisted men were tried and punished for committing numerous atrocities and war crimes. In 1949, the trials ceased, with a total of 5,700 cases having been heard.Major General Tomitarō Horii did issue a "Guide to Soldiers in the South Seas", in late 1941, which ordered troops not to loot or kill civilians. This order was intended to prevent a repeat of atrocities that the Army committed in China; however, the order only affected men under his command.
Several reasons are given for the especially brutal and merciless behavior exhibited by many members of the IJA towards their adversaries or non-Japanese civilians. One is probably the brutal behavior that they themselves experienced. The IJA was known for its extremely harsh treatment of enlisted soldiers from the start of training, including beatings, unnecessarily strenuous duty tasks, lack of adequate food, and other violent or harsh disciplinary tactics. This was contrary to the Imperial Rescript to Soldiers and Sailors of 1882, which instructed officers to treat subordinates respectfully. Not until 1943 did the senior command realize this brutality had an effect on morale and ordered an end to it, an order which was routinely circumvented or ignored in the field.
During the Pacific War, the Imperial Army's reputation for refusing to surrender was established by the few Japanese survivors of numerous battles throughout the Pacific campaign: 921 captured out of a garrison strength of 31,000 in the Battle of Saipan, 17 out of 3000 in the Battle of Tarawa, 7,400–10,755 out of 117,000 in the Battle of Okinawa, with a high number of battlefield suicides sanctioned by the Imperial Army. The spirit of gyokusai saw commanders order suicidal attacks with bayonets, when supplies of hand grenades and ammunition were still available. In the South West Pacific Area, just over 1,000 surrendered in each of 1942 and 1943, around 5,100 in 1944, and over 12,000 in 1945, and might have been greater except for disease. Propaganda through leaflet drops by the Americans accounted for about 20% of surrenders, equating to about one POW for every 6,000 leaflets dropped; while the Japanese objected to the "unscrupulous" leaflets, which contained some truth with regard to the willingness of American forces to accept surrenders from the Japanese. This was in contrast to Imperial Japanese Army's practice of depicting American troops as cruel and merciless, referring to them as 鬼畜米英 and informing their own troops that Americans would rape all captured women and torture the men, leading directly to brutal Japanese treatment of POWs in incidents such as the Bataan Death March and the mass suicide of Japanese soldiers and civilians during the battles of Saipan and Okinawa. However, this perception was not entirely unfounded, as many captured Japanese were executed, and their teeth and skulls were often extracted as trophies.
Various sex crimes were committed against women in Korea and China. The Japanese forcibly used women taken from Korea and China as sex toys. In addition, members of the Japanese Army committed various crimes against civilians in Korea and China. In one such example, Japanese soldiers forcibly abducted Korean girls and forced them to eat human flesh soup They also formed Unit 731 to conduct numerous biological tests on civilians and Prisoners of War. They called the subject of the experiment a 'log'.'Patients' included the elderly, women, and children, and they would undergo disfiguring experimentation with no anaesthetic.
Imperial General Headquarters and the role of Emperor Hirohito
During the first part of the Shōwa era, according to the Meiji Constitution, the Emperor had the "supreme command of the Army and the Navy". Hirohito was thus legally supreme commander of the Imperial General Headquarters, founded in 1937 and wherein the military decisions were made.Primary sources such as the "Sugiyama memo", and the diaries of Fumimaro Konoe and Kōichi Kido, describe in detail the many informal meetings the Emperor had with his chiefs of staff and ministers. These documents show the Emperor was kept informed of all military operations and frequently questioned his senior staff and asked for changes.
According to historians Yoshiaki Yoshimi and Seiya Matsuno, Hirohito authorized, by specific orders transmitted by the Chief of staff of the Army such as Prince Kan'in or Hajime Sugiyama, the use of chemical weapons against Chinese civilians and soldiers. For example, Hirohito authorized the use of toxic gas on 375 separate occasions during the invasion of Wuhan in 1938. Such weapons were also authorized during the invasion of Changde.
According to historians Akira Fujiwara and Akira Yamada, Hirohito even intervened in planning some military operations. For example, Hirohito pressed Field Marshal Hajime Sugiyama, four times during January and February 1942, to increase troop strength and launch an attack on Bataan. In August 1943, he scolded Sugiyama for being unable to stop the American advance on the Solomon Islands and asked the general to consider other places to attack.
Only in rare moments of special importance were decisions made in Imperial council. The Imperial government used this special institution to sanction the invasion of China, the Greater East Asia War, and Japan's surrender. In 1945, executing a decision approved in Imperial council, Emperor Shōwa, as commander-in-chief, ordered, for the only time directly via recorded radio broadcast to all of Japan, the surrender to United States forces.