The was based on an already existing reinforced Type 97 Chi-Ha medium tank chassis developed by the

Imperial Japanese Army The was the official ground-based armed force of the Empire of Japan from 1868 to 1945. It was controlled by the Imperial Japanese Army General Staff Office and the Ministry of the Army, both of which were nominally subordinate to the Emperor ...

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...

Development

Inspired by the Grille series of

self-propelled artillery Self-propelled artillery (also called locomotive artillery) is artillery equipped with its own propulsion system to move toward its firing position. Within the terminology are the self-propelled gun, self-propelled howitzer, self-propelled mo ...

vehicles developed by

Nazi Germany Nazi Germany (lit. "National Socialist State"), ' (lit. "Nazi State") for short; also ' (lit. "National Socialist Germany") (officially known as the German Reich from 1933 until 1943, and the Greater German Reich from 1943 to 1945) was ...

during

, wherein a

15 cm sIG 33 The 15 cm sIG 33 (''schweres Infanterie Geschütz 33'', lit. "Heavy Infantry Gun") was the standard German heavy infantry gun used in the Second World War. It was the largest weapon ever classified as an infantry gun by any nation.Hogg, p. ...

infantry support gun Infantry support guns or battalion guns are artillery weapons designed and used to increase the firepower of the infantry units they are intrinsic to, offering immediate tactical response to the needs of the unit's commanding officer. They typicall ...

was mounted on a tracked chassis, engineers at the Army Technical Bureau resolved to do the same. Just like the German Grille, the Ho-Ro was based on an already existing chassis. Production was assigned to

Mitsubishi Heavy Industries is a Japanese multinational engineering, electrical equipment and electronics corporation headquartered in Tokyo, Japan. MHI is one of the core companies of the Mitsubishi Group and its automobile division is the predecessor of Mitsubishi Moto ...

. The exact number produced is uncertain, but 12 units were built in 1944.Taki's Imperial Japanese Army Page: "Ho-Ro"
/ref>

Design

The chassis selected was a modified Type 97 Chi-Ha medium tank chassis. On to this platform, a Type 38 150 mm howitzer based on a design by the German arms-manufacturer

Krupp The Krupp family (see pronunciation), a prominent 400-year-old German dynasty from Essen, is notable for its production of steel, artillery, ammunition and other armaments. The family business, known as Friedrich Krupp AG (Friedrich Krupp ...

was mounted, but dated from 1905 and had been withdrawn from service as being obsolete in 1942. The main gun could fire Type 88 APHE rounds and

HEAT In thermodynamics, heat is defined as the form of energy crossing the boundary of a thermodynamic system by virtue of a temperature difference across the boundary. A thermodynamic system does not ''contain'' heat. Nevertheless, the term is ...

rounds, if necessary. Given its breech loader, the maximum rate of fire was only 5 rounds per minute. The gun's elevation was restricted to 30 degrees by the construction of the chassis. The restricted elevation meant it was capable of firing a 35 kilogram shell 6,000 meters (6,600 yards). Other design issues included the fact that although the gun crew was protected by a

gun shield A U.S. Marine manning an M240 machine gun equipped with a gun shield A gun shield is a flat (or sometimes curved) piece of armor designed to be mounted on a crew-served weapon such as a machine gun A machine gun is a fully automatic, ri ...

with armor thickness of 25 mm at the front, the shield with armor thickness of 12 mm only extended a very short distance on the sides; leaving the rest of the sides and back exposed. In addition, the Ho-Ro did not have any secondary armament, such as a

machine-gun A machine gun is a automatic firearm, fully automatic, rifling, rifled action (firearms)#Autoloading operation, autoloading firearm designed for sustained direct fire with rifle cartridges. Other automatic firearms such as Automatic shotgun, a ...

, making it vulnerable to close combat. Top-angle view of Type 4 Ho-Ro

Combat history

The Type 4 Ho-Ro was rushed into service, deployed and saw combat as part of the 2nd Tank Division with the Japanese Fourteenth Area Army during the Philippines Campaign in the last year of

. Remaining units were deployed to

Okinawa is a prefecture of Japan. Okinawa Prefecture is the southernmost and westernmost prefecture of Japan, has a population of 1,457,162 (as of 2 February 2020) and a geographic area of 2,281 km2 (880 sq mi). Naha is the capital and largest city ...

in ones and twos for island defense during the

Battle of Okinawa The , codenamed Operation Iceberg, was a major battle of the Pacific War fought on the island of Okinawa by United States Army (USA) and United States Marine Corps (USMC) forces against the Imperial Japanese Army (IJA). The initial invasion of ...

, but were severely outnumbered by American artillery.

Surviving example

The only known surviving example of a Type 4 Ho-Ro is located at the American Heritage Museum in Stow, Massachusetts. It is currently on loan from the

National Museum of the Marine Corps The National Museum of the Marine Corps is the historical museum of the United States Marine Corps. Located in Triangle, Virginia near MCB Quantico, the museum opened on November 10, 2006, and is now one of the top tourist attractions in the st ...

and was captured on the island of

Luzon Luzon (; ) is the largest and most populous island in the Philippines. Located in the northern portion of the Philippines archipelago, it is the economic and political center of the nation, being home to the country's capital city, Manila, ...

in the

Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...

Notes

References

* * *

External links

Taki's Imperial Japanese Army Page - Akira Takizawa
{{WWIIJapaneseAFVs World War II self-propelled artillery 150 mm artillery Mitsubishi Military vehicles introduced from 1940 to 1944