Experimental First Tank
The tank was one of the remarkable innovations during WWI. The IJA heard about the power of tank in the battle, they imported some tanks to know what is the tank. First, one British Mk.IV was imported in 1918. In those days, no Japanese could operate the tank. The tank was operated by the British engineers and demonstrated before Japanese people being astonished at a moving iron monster. After British Mk.IV, some other tanks were also imported. Japanese learned the tank by these imported tanks.
In 1925, the IJA decided to establish the tank force. They planned to form there light tank battalions and one heavy tank battalion. However, the problem was how to prepare tanks for these units. In those days. there were only 16 tanks in Japan. The IJA sent a mission to Europe in order to import more tanks from UK or France. They requested new models of the tank, but European countries would not sell new models because they were not yet enough produced. After all, only available model was the old Renault FT17 tank. The IJA was reluctantly importing them for their tank force.
To know this course, young engineers in the IJA Technical Bureau got angry and insisted that the tank should be made in Japan and they could do it. General Suzuki, the chief of the IJA Technical Bureau made a protest against the IJA Department and made its decision cancelled. After it, they were allowed to develop a tank, but it was a heavy bet for them. Until that time, IJA engineers had developed only a few kinds of truck and one kind of tractor. Of course, no one had an experience to develop the tank. Moreover, they had to achieve it only in two years. If they could not do it within this period, the budget for the development would be cancelled.
The development of the Japanese tank started in June 1925. Four engineers in the motorcar group of the IJA Technical Bureau participated in the development. One of them was young officer Tomio Hara. Later, he became a general and the leader of the Japanese tank development. They started to design a tank and worked hard day after day. There was no previous example of the design of tank in Japan, so they had to design every things, even one bolt and one nut. They drew plans for 10,000 pieces of parts.
In May 1926, the design was finished and it was ordered to the Osaka Arsenal. In those days, Japanese technical level of the motorcar was very low and no motorcar company nor factory existed in Japan. The Osaka Arsenal had solved many technical problems one by one with much efforts. In Feb. 1927, the first Japanese tank was finally finished within the required period. It was a big news that the tank was made in Japan. Many IJA generals requested to attend the test of the first Japanese tank. On June 21st, the first Japanese tank run smoothly in the front of attendant generals. The generals applauded it, because they had been afraid that it would really run. In the test of the next day, the tank showed a satisfactory performance on the movement in rough terrains and slopes. The first Japanese tank made a great success. It proved that Japan can develop the tank by themselves. After that, it became the IJA policy that the tank is made in Japan.
Though the first Japanese tank was made, it was too big and too heavy (18 tons) to use as main tank in the army. So, a light tank at 10 tons weight was newly designed. The development of the new tank advanced swiftly because the designers have had an experience to develop a tank. Only problem was the armor plate for tank, because the first tank was made of soft iron. The armor plate was developed by the Nihonseikosho Company. So, it was called the Niseko steel, abbreviated as NIhonSEiKOsho.
In April 1929, a new light tank was finished. Its weight was 9.8 tons. It was called Type 89 Light Tank. Later, it was re-classified to the medium because the weight increased to over 10 tons due to several improvements. The production of Type 89 Tank started in 1931 and it became the main tank of the IJA. On the other hand, the first tank developed to the Type 95 Heavy Tank. However, the IJA had no interest in the heavy tank and it was produced in only small numbers.
Type 89 Tank was deployed in the tank force and used in the battles of China. First, the tank force belonged to the infantry arms and their duty was to support infantry. The short-barreled 57mm gun of Type 89 Tank was effective to destroy the enemy MG nest and the 15mm-thick armor was enough for the enemy HMG fire. Its low speed of 25km/hr was not a problem for the infantry support duty.
Type 89 Tank was apparently superior to Renault NC27 tank, which was used together with Type 89 in China. Soon, Renault tanks were replaced with Type 89 Tanks. Though the Type 89 Tank was good on the whole, there were still several small problems. For example, early model had a gap under the muntlet and a bullet flies into a turret through that gap. As the Type 89 Tank was continued to be improved after the production started, many variations existed in Type 89. The development of the Japanese tank was still at the stage of trial and error.
After WWI, European countries attempted to mechanize the cavalry. The horseman was useless in the modern warfare. To know this tendency in Europe, Japanese cavalry also tried some armored cars for their mechanization. However, the wheeled armored car was not fit to the operation in China, because the roads in China were very poor. They gave up the wheeled armored car and studied the tracked armored car. First, they experimented with amphibious cars. The first amphibious armored car was a curious vehicle having both track and wheel and it run in the opposite direction on the water and on the ground. After this, some amphibious cars were experimented, but any car could not satisfy the cavalry. At last, they gave up the amphibious car and decided to make a new tracked vehicle only for ground.
New vehicle was ordered to Ishikawajima Motorcar Manufacturing Company and it was finished in 1932. It is Type 92 Combat Car. It was called " Sokosha"(Armored Car) in Japanese, but it was actually a light tank. Type 92 was thin-armored and light-armed, but it was able to run at 40 km/hr. It was a vehicle fit to the cavalry spirit. Type 92 was used in China by cavalry.
Experimental Amphibious Armored Car Sumida AMP
The IJA imported two Carden Loyd Mk.VIs in 1930 and put them in the IJA Infantry School and Cavalry School for evaluation. The schools tested them and reported that this kind of vehicle will be useful as the support vehicle for transport, scout and communication.
According to this report, the IJA decided to develop the same kind of vehicle as Carden Loyd. The development was ordered to Tokyo Gasu Denki Kogyo Inc. in 1933. The experimental model was finished in 1934. It was a light small vehicle like Carden Loyd, but it had a turret armed with one MG. To carry the cargo, it drew a trailer. That vehicle was called "Tokushu Keninsha" (Special Tractor), or abridged to TK.
Seeing this vehicle, the General Staff Office thought it too luxurious to use it only as tractor and they required to rename it as armored car. So, it was named Type 94 Light Armored Car when TK was introduced. Though it is the correct Japanese name, it is called tankette here as generally called.
Type 94 Tankette was the cheap vehicle, about a half price of Type 89 Medium Tank. So, it could be many deployed. The IJA established the training center of tankette in eleven infantry divisions and popularized the armor in the army. Type 94 Tankette was mass-produced, 300 pieces in 1935, 246 in 1936 and 200 in 1937. They were deployed in the independent tankette company under the infantry division. The infantry division could use the tankette unit at will, so it was a very convenient unit for infantry. Type 94 Tankette was used not only for support duty, but also for combat. Type 94 Tankette much contributed to the mechanization of the IJA infantry.
A Vickers Mk.C tank was imported to Japan in 1927. When British engineers operated it in the presence of IJA officers, the tank caught fire and British engineers got badly injured with fire. This accident reminded the Japanese of the danger of the gasoline engine.
The diesel engine uses the light oil, which is less inflammable than gasoline. However, the first diesel engine for vehicle in the world just appeared in 1924 and the diesel engine was not popular in those days. Tomio Hara insisted the development of the diesel engine for tank, but the most people said that it was too risky because any country had not yet succeeded in the diesel engine for tank. Hara eagerly persuaded the opponents by pointing out the merits of the diesel that the diesel is more safe than gasoline engine and the diesel can save the consumption of precious oil that was all imported to Japan. In 1932, the development of diesel engine was approved. However, one important condition was added. The IJA required the air-cooling engine. It is because of the condition of Manchuria. There are many desert terrains without water and the winter of the Manchuria is so cold that expensive antifreeze is necessary for the water-cooling engine.
The development of the diesel engine was ordered to Mitsubishi Jukogyo Company. After efforts in two and a half years, Mitsubishi had accomplished the development of diesel engine. It was an air-cooling 120HP diesel engine called Mitsubishi A6120VD. It was loaded in the Type 89 Medium Tank from the 1934 production. Then, it was also used by the Type 95 Light Tank. This engine was reliable and easy to maintain. The success of the long march of the tank forces like Malaya campaign much owed to this engine. And the diesel engine decreased the danger of fire. 21 out of 28 Type 89 Otsu Tanks destroyed in Nomonhan were recovered because they did not catch fire. The disadvantage of the diesel engine is that it is underpower compared with gasoline engine. It made difficult for the Japanese tank to have the heavy armor and large gun.
After that, all Japanese military vehicles, tank, tractor and truck came to load a diesel engine and several companies produced diesel engines. Since they produced different kinds of diesel engine, it made a large problem. For example, Type 97 Medium Tank loaded two kinds of diesel engine made by Mitsubishi and Hitachi. The parts of these engines were not compatible and it made problemsome to maintain the tank. In 1940, the IJA showed the standard of the diesel engine for the military vehicles. This standard unified the basic parts like cylinder and covered some sizes of engine from 4 to 12 cylinders. This type of engines were called "Tosei" Engine. It was applied from the engine of Type 1 Medium Tank.
From early 1930s, the IJA was experimenting on the mechanized unit combined with infantry and tank. However, slow Type 89 Medium Tank could not keep pace with the motorized infantry which could move at 40km/hr by truck. To know this problem, Tomio Hara proposed a new light tank at 40km/hr speed and started the development in 1933. The prototype of the new tank was finished in 1934. It was a high-speed and light-armored tank similar to the British cruiser tank or Soviet BT-tank. Its code name was "Ha-Go" meaning the third car.
In 1935, the IJA council about the introduction of Ha-Go was held at the IJA Technical Bureau. At that meeting, Ha-Go was presented as the main tank of the mechanized unit. The representative of the tank force objected that this tank cannot be used as main tank, because its armor is not enough for the infantry support duty. The representative of the cavalry said, "We don't care of a thin armor. We are content with its speed and armaments." The chairman asked the representative of the tank force if this tank is unnecessary for them. The representative of the tank force said unwillingly that it would be better than not having it, because it would be used as armored car.
Ho-Go was introduced and named Type 95 Light Tank. Though it was not a main tank, Type 95 was produced in the most numbers among the Japanese tanks.
Prototype of Type 95 Light Tank
Since the Ha-Go was not adopted as the main tank of the tank force, the successor to Type 89 Medium Tank was needed. However, there were two different opinions on the new main tank. The IJA Department requested a low-price tank due to the limited budget and the Staff Office agreed with it because they made much of the quantity. On the other hand, the tank force made much of the quality and was opposed to a low-price tank.
As they could not consent easily, two different prototypes were made. One was called Chi-Ha and another was called Chi-Ni. The prototype of Chi-Ha was 13.5 tons, 35km/hr and had a two-men turret. Chi-Ni was 9.8 tons, 30km/hr and had a one-man turret. The armor of both prototypes was 25mm-thick. Though the tank force had requested a 30mm-thick armor, they forbore with 25mm because of the weight increase.
The problem of the new main tank was solved by the outbreak of the Sino-Japanese War. The budget of the IJA was increased sharply and the IJA Department agreed with the introduction of Chi-Ha. The production of Type 97 Medium Tank started in 1937 and it became the main tank of the IJA after Type 89 Medium Tank.
Experimental Medium Tank Chi-Ni
Type 97 Medium Tank was much superior to Type 89 Medium Tank with regard to the most points. However, it was armed with the same short-barreled 57mm gun as that of Type 89. The designer Hara was not satisfied with it and thought that the coming tank should be armed with a high-velocity cannon for anti-tank fight. However, the IJA did not understand it and they were satisfied with the gun of Type 89 Medium Tank. Their main interest was in the battles of China and there was no tank vs. tank fight.
Hara's anxiety came true in the battle of Nomonhan. The 45mm gun of Soviet tank outranged the short-barreled gun of Japanese tank and the Japanese tanks were suffered in heavy losses. From this lesson, the IJA awoke to the tank vs. tank fight and they started the development of a new tank gun.
New tank gun was 47mm caliber lesser than 57mm tank gun, but it had a long barrel and its penetration was much superior to that of the short-barreled 57mm gun. The development of the 47mm tank gun started in 1939 and it was finished in 1941. When the Pacific War began, the Chi-Ha loading a new turret (Shinhoto) armed with a 47mm gun was being tested. The Japanese tanks which invaded the Philippines encountered US M3 Light Tanks. M3 Light Tank had a thick armor and the Japanese tank gun could no penetrate its armor. To defeat the M3 Light Tank, the Japanese transported Shinhoto Chi-Ha tanks to the Philippines in a hurry. On the Philippines, the 47mm gun of the Shinhoto Chi-Ha was tested against the captured M3 Light Tank. At 1,000m distance, 3 out of 6 hits penetrated the front armor of M3 Light Tank. And 6 out of 9 hits penetrated it at 800m distance. Japanese tankers were satisfied with the result and they were burning with revenge to M3 Light Tank. However, the battle of the Philippines ended without the fight of M3 Light Tank vs. Shinhoto Chi-Ha.
Japanese SP gun was also born from the lesson of Nomonhan. In Nomonhan, Japanese artillery were outnumbered by Soviet artillery and suffered in heavy losses. After the battle of Nomonhan, the buildup and mechanization of the artillery force were stressed in the IJA. To mechanize the artillery, SP gun was necessary, but the Japanese did not have this kind of vehicle.
The first developed SP gun was the Type 1 SP gun. It had two versions, 75mm gun model and 105mm gun model. At first, they were planned to be used in the Pacific as assault gun. However, Since the early campaigns in the Pacific War ended in a short period, they were not in time for these campaigns. When the tank divisions were formed, they were deployed in the mobile artillery regiment of the tank divisions. Though the SP gun was expected as the main weapon in the mobile artillery unit, it was produced in only small numbers. In 1943, the IJA suppressed the production of the armor severely in order to increase the production of airplane. The 1943 production plan of the IJA stated "We put up with it if this decision will affect the production of Type 1 SP Gun."
Though the SP gun was once suppressed, it was revived as tank destroyer. From the late 1943, a lot of M4 Sherman Tank appeared in the Pacific and Burma and they raged in the battle ground. The 47mm tank gun was inadequate against M4 Sherman and more powerful gun was urgently required. The IJA restarted the production of Type 1 SP Gun and ordered the IJA Technical Bureau to improvise the SP gun mounting an obsolete artillery on an obsolete tank chassis. The stuffs of the 4th Laboratory of the Technical Bureau, saying ironically that it is the marriage of a widow and a widower, developed two SP guns, Ho-Ro and Ho-To. Ho-Ro was mounted a Type 38 15cm Howitzer on the Chi-Ha chassis and Ho-To was mounted a Type 38 12cm Howitzer on the Ha-Go chassis. They are old guns which were introduced before WWI. They are low-velocity, but the HEAT shell enabled them to destroy the M4 Sherman.
Besides these improvised SP guns, a heavy tank destroyer was planned. It was mounted with a 105mm anti-tank cannon and had a closed fighting compartment. This vehicle called Ho-Ri was intended to match against the M23 Pershing.
12cm SP Gun Ho-To
In 1942, new medium tank Chi-He had been developed. It was better than Chi-Ha on the speed or armor, but the IJA had little interest in this new tank. The 47mm gun of Chi-He was already mounted on Chi-Ha and the factories were mass-producing the Chi-Ha. Almost two years after its development, the production of Chi-He was started. However, Chi-He was not produced even for one year because the production of Chi-Nu started.
Type 3 Medium Tank Chi-Nu was urgently developed to cope with the M4 Sherman. Originally, the next tank to Chi-He was the Type 4 Medium Tank Chi-To. However, the development of Chi-To delayed and a stopgap tank was required. The development of Chi-Nu started in May 1944 and it was finished in Oct. It took only a half year, as Japanese engineers rushed work. Chi-Nu was produced until the war ended. Chi-Nu was the last tank that was deployed in the Japanese tank forces.