Sunday, September 3, 2017

The Ho-Ri Tank Destroyer

        Hello everyone. The last time I posted a write on the Ho-Ri tank was on November 14th, of 2016. Since then my studies on the project have been underway for quite some time. Earlier this year, I obtained documentation files on the tank project from a private collection. In my findings were official schematics and outline drawings of the Ho-Ri tank destroyer, alongside two photographs of the vehicles construction. However I was not given the permission needed to obtain rights to these photographs, I was able to secure property rights to its drawings. Which unfortunately, I do not plan to release publicly for the time being. 

This article will be a brief historical background on the Ho-Ri as of what I have learned since last year. The previous article, no longer being completely up-to-date, will be edited as such and forwarded to this new post - as to clear future confusion. I hope you all enjoy!

- Information on vehicle accurate as of [9/3/2017] -

As the war progressed in the Far East, it became increasingly evident that Japan’s armored warfare doctrine would not suffice against the growing threat from the United States. Prior to America’s declaration of war on Japan, tank doctrine focused solely on the infantry support role during an offensive. Much of the Japanese armor inventory in 1941 was already a decade old. Poorly armed and armored, these Japanese infantry tanks could not counter the M4 Sherman. To remedy this, Japan quickly introduced the Chi-Ha Kai with a 4.7cm anti-tank gun, but it was only a temporary solution.

Japanese crew manual on the M6 Heavy Tank. 
Japanese Intelligence also became aware of the development of the M6 Heavy tank. If such a vehicle was sent to the Pacific, few of the Imperial Japanese Army’s anti-tank guns would have been capable of stopping it at average combat distances. Japan’s military leaders and weapons manufacturers thus realized that they would need more potent tanks with better armor and cannons. After a careful review of German tank doctrine, the Japanese Weapons Administration Headquarters enacted a new tank doctrine in July of 1943.

This new policy focused on the development and deployment of a common medium tank with stronger armament, which would in turn be supported by tank-destroyers with high-caliber weaponry. In furtherance of this policy, both medium and large caliber anti-tank guns were developed for use in new medium tank designs in 1943. Two medium tank designs were selected, the Chi-To and Chi-Ri tanks both adopted their versions of the Type 5 75mm guns.

Development of the Ho-Ri began in late 1943, using the chassis of the Chi-Ri as the base for development. Japan’s 4th Technical Institute of Research understood that the Chi-Ri’s relatively flat front hull plates offered little protection against enemy anti-tank fire. Initial tank designs kept an unchanged hull design, and replacing the turret with a welded casemate. A key focal point in the design of the Ho-Ri was the decision to angle the front armor plate to 70 degrees, drastically increasing the effective armor protection and enabling the vehicle to withstand American 76mm guns.

The concept was presented to the Ministry of War in early 1944 in the form of a wooden mockup. The staff had expressed positive opinions on the vehicle design. Following the presentation, the order to construct a prototype of the Ho-Ri was approved. It took until July for the chassis to be completed. In August, the Ho-Ri prototype had been assembled and put through trials.

National Archive File Ref. C14011075200
The National Institute for Defense Studies
Ministry of Defense, Military Administration
 of Ordnance, 4th Technical Research Institute
 Report Ho-Ri Prototype.

Weighing in at approximately 35 tons, the prototype successfully completed trials with flying colours. The tank had similar armor protection to that of the Chi-Ri, keeping a thickness of 75 millimeters at the front hull plate, with the superstructure at 120 millimeters. The top speed recorded from trials was 40 kph using a Kawasaki Water-Cooled V12 Engine, identical to that of the Chi-Ri medium tank, with a power output of 550 horsepower.

The Ho-Ri prototype mounted an Experimental High Velocity 10.5cm anti-tank gun, which featured a semi-autoloader mechanism to reduce the strain of loading the heavy shells. The gun was designed to counter all fielded armored vehicles the Unites States had in its possession. Japanese Intelligence had been aware of the possible deployment of the M26 Pershing and the M6 Heavy tank in the pacific for the invasion of the mainland. Due to the size of the 10.5cm cannon, natural depression was limited to only a couple degrees. To counter this, there was a top roof hatch that opened by pin to allow full depression of the gun.

The gun was required to effectively penetrate and destroy these tanks at all reasonable combat ranges at most angles. Development of this Experimental 10.5cm anti tank gun was initiated on July 30th, 1943. One member of the development team was a Major of the Army Weapons Administrative Division, and had stated in his records the gun had to achieve a performance figure of 200 millimeters of penetration against RHA at a range of 1,000 meters. With this demand being kept in mind, the first prototype cannon was completed and tested in February of 1944. It lacked sufficient performance, only being able to fire at a muzzle velocity of 916 m/s. It was only capable of penetrating 150 millimeters of armor at the trial range of 1,000 meters. Without a ballistic cap, the performance of its APHE shell at certain angles was drastically poor. The Munitions Council had to alter the design of the experimental gun and work on producing a new one for the Ho-Ri project.

The Ho-Ri tank drawn in the same style as Tomio Hara.

After trials were conducted with the constructed prototype, the Ho-Ri was approved for planned production, and was to be officially adopted into service under the designation Type 5. The Army Weapons Administrative Division listed concerns they had in mind with the prototype to be adjusted with the production of the main series of tank destroyers. Due to rapid development of American anti-tank weaponry, it was ordered to increase the thickness of the Ho-Ri’s armor. However due to the war's end drawing near for Japan, the lack of materials presented an issue for a quantitative supply of Ho-Ri units to be supplied to tank regiments. The choice was then made to limit the number of production models and for them to be kept reserved in vital focal areas of the Japanese mainland. This order was in line with the limited production run of the Chi-To and Chi-Ri tanks.

National Archive File Ref.C13120839500, The National Institute for Defense Studies, Ministry of Defense,
Military Administration of Munitions Mobilization, Production Chart of January to April of 1945.

The thickness of the front hull plate was increased to 120 millimeters for the production model. The sides and angled plating around the vehicle were thickened to a considerable degree as well. This caused the vehicle to have a drastic increase in weight and it would have been underpowered with the old engine. To compensate for the added weight, an Experimental Kawasaki V12 engine with an output of 1,100 horsepower was added. This kept the mobility of the production model Ho-Ri on par with that of the original prototype.

The Experimental 10.5cm anti-tank cannon continued to be developed by the Munitions Council throughout 1944. In December of the same year, the project was once again at a testing phase with a new prototype gun. Performance of this gun reached the required standards - 200 millimeters of penetration at 1,000 meters with a muzzle velocity of 1,005 m/s. The gun was supplied with the Type 2 APHE shell with a ballistic cap to support the trajectory of the shot. It was accepted into service as the Type 5 10.5cm Tank Gun. By the wars end, only a few models of the gun were produced. And a limited supply of tank rounds.

Production of the Type 5 Ho-Ri began in January of 1945. By March, a total of 5 Ho-Ri tanks had been completed; further production of the vehicle was halted by American bombing raids. Japan would not be able to continue production of the vehicles as the Japanese war effort was almost bled dry by this point. The 5 completed Ho-Ri’s were kept with the Chi-Ri and Chi-To tanks at local armories. None of the vehicles were given to standard tank groups. Instead they remained as property under the Munitions Council and supervised by officers of the local battalions.

Lake Hamana in Shizuoka Prefecture. The town has a
reputation for its mysterious sunken tanks deep
in the lakebed.
Some of the built tanks were deployed to Shizuoka Prefecture in August of 1945. The military ordered the sinking of a Chi-To along with two other large vehicles in the lake of Hamana. It is believed that a Ho-Ri tank destroyer was sent with two Chi-To units to the region. The tanks were ordered to be sunken in a deep-water lake in order to prevent the United States military from obtaining them. Two other deployment zones were theorized by post-war Japanese University thesis's; Kanagawa and Osaka Prefectures, where the locations of the Sagami and Osaka arsenals were based. The division of tanks from the Archive mentioned a single Ho-Ri unit with a complement of 2-3 tanks of varying class, Chi-Ri’s or Chi-To’s. The Ho-Ri was to be kept in the rear while the medium tanks were to be placed on the front line to engage enemy armor.

By the end of the war almost all Ho-Ri’s and other end war vehicles were either scrapped, destroyed, or sunk. Leftover prototype and testbed vehicles were captured and brought back to the United States where after being evaluated, quickly scrapped for parts in the years following. As of September 3rd, 2017, there are currently only 2 photographs of the Ho-Ri’s in possession of private collections. Public access to these photographs and other documentation (such as the blueprints and data sheets) are now under review.

- Information on vehicle accurate as of [9/3/2017] -


  1. Ho-ri is japanese waffen trager?

    1. If anything it's more like a Japanese Jagdpanther seeing as they are both closed-topped, relatively well-armored tank destroyers based on the chassis of a medium tank.

  2. Fascinating stuff as always. Really looking forward to when those two pictures of the Ho-Ri under construction are released to the public. It's too bad the search of Lake Hamana in 2013 never turned up anything though, especially since it'll probably be a while until the next search.

    Also, I didn't realized the roof coming up for maximum gun depression was a feature of the tank, from the reddit posts I saw about that on the test server I thought it was Gaijin messing up the model again. Speaking of which, do you happen to know the horizontal and vertical gun traverse of the Ho-Ri?

    1. thankfully it was just the premium variant while the regular/researcheable/progression will be the "upgraded" "pre-production/production" Ho-Ri

  3. Call a team, bring a submarine, and prove them that this tank existed )

    1. they already know it existed since there are official reports of it's existence, what they could do is try to salvage them like the russians keep doing by taking KV-1s, BT-7s, etc... out of lakes, rivers or ponds
      it would be especially important if one of those was a Chi-Ri because of the stupid *ss thing the US did to the prototype they captured, nuked and then scrapped it

    2. *I wrote ponds but was thinking of swamps, they keep finding them, they also found a rare M4 variant that was only supplied and used by the soviets

  4. amazing read as always but it made me curious about something, being the Ho-Ri, Chi-To and Chi-Ri part of the revised tank doctrine and having them come to the conclusion that there was need for increased protection in the form of sloped armor for the Ho-Ri did they never try to apply the same idea to the Chi-Ri and Chi-To?
    sloping armour also means reducing the volume of resources needed to achieve the same or even superior degree of protection, so, are there no hints the possibility for such might have been discussed for other tanks?

    1. I think there's a Japanese tank called the Chi-Se that used the Ho-Ri Hull with a Chi-Ri ii turret and a 10cm type 5, however I'm not entirely sure it was ever constructed, or it is pure fantasy.

    2. I've seen the Chi-Se circuling online but havenever read anyone who has been actively researching Japanese tanks confirm it, be it Eun Ae Sun or previously Digensui who also researched them for WoT, so far Ive only read something about the Chi-Ri with the modified 88mm AA gun being a fake (you can commonly find it online as Chi-Ri Kai, also on wikipedia)

      as Mai_Waffentrager as revealed she has been kept busy with other things so we can only wait that new documents get released and a accurate book becomes available AT LEAST in english or that someday in the future she will write about it and dismistify what the internet thinks it knows about the Chi-Ri and anything that might have derived from it

    3. *have never
      it seems I type too fast for my keyboard to follow

  5. Its funny how you have convenient excuses as to how there are 0 in existence. This mock up that dreams to be a tank will only see the light of day in games that choose to bring fictional and blueprint tanks to life with guesses and estimates on armor and performance of the "tank" as a whole.

    1. The moment you start arguing with an ignorant fool, you have already lost.

    2. I wonder if you are one of those «supporters of true historical balance/matchmaking» that 72 years after the end of the still have not noticed the basic rule for weaponry development, new weapons/vehicles are not developed to be on par with the enemy but to surpass them, for that reason you cannot balance a VEHICLE BASED GAME on the fact that vehicle A fought vehicle B alone because vehicle C also fought vehicle B and to have a matchmaking where A will always go against B you have to include C because IRL it always was against B, take A, B and C as vehicles representing 3 eras of WWII vehicles (like interwar, early WWII and late war designs)

      despite all that the main reason why a historical MM would not work has been proven time and time again during many WT events, especially the "historical capaigns", the truth is that only a really small % of the players are willing to play on the team with the disadvantage so that at least a few can try the event, if they were allowed to everyone would qeue for the team with T-34's and KV-1's instead of the team with Pz.IV's with the short 75mm gun or Pz.III's with the 37mm or shorter 50mm guns
      that is why Gaijin took measures to "block" access to the top tank on each historical event so that you would not get everyone qeue on the side that can use Panthers and Tigers against T-34 (1941) and KV-1 L-11, that is why you now have to work to get SP like in GF RB and even still the number of top BR tanks per team is limited to 2 or 3

      this might be a bit long but historical balance/matchmaking has been proven to not work because even the players themselves do not wish for that, as proven to the very few who play the side at disadvantage, and if you create a category based on a vehicle performance (aka BR/tiering) while only using vehicles who fought in any kind of war or was at east used for training by a army you would find that on each tier there would be a vehicle clearly superior to others and no direct threat to it's superiority from the other nations, that is why prototypes are a "god given" gift to a company that desires to make a casual vehicle based game, this alows players to quickly find a new match while still working to unlock the next vehicle without going through too much "pain", because it would be really "interesting" to go from a M3 Lee to a M6 and then fight Tiger II's with it

    3. *"historical caMpaigns"
      *"or was at Least used", since I cannot edit the comment above

  6. I really like to see some detailed information about Chi-To and Chi-Ri projects. In my own discovers through the ethernet, i found that theres no sures about some model names etc.

    And why does Gaijins call Chi-Ri in War Thunder as Chi-Ri II? It's confused me in a first place.

  7. So the 10.5 cm cannon doesn't get a semi-automatic loader system to help the crew load a big shell? I'm confused haha

  8. I'm a bit confused which version of the Ho-Ri this is. In your previous article, you went through the different versions of the Ho-Ri. Going off that, the Ho-Ri currently in-game would be the Ho-Ri III. But you don't mention these versions in this article, and you said that your last article is inaccurate. So does this mean that this is not the Ho-Ri III? I'm just trying to get the most accurate information, and it would be nice if you could clear up some confusion. Thank you in advance.