The was an

anti-aircraft gun Anti-aircraft warfare, counter-air or air defence forces is the battlespace response to aerial warfare, defined by NATO as "all measures designed to nullify or reduce the effectiveness of hostile air action".AAP-6 It includes surface based, ...

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 o ...

. They started producing the gun in 1943. The Type 4 number was designated for the year the gun was accepted, 2604 in the Japanese

imperial year The , colloquially known as the or "national calendar year" is a unique calendar system in Japan. It is based on the legendary foundation of Japan by Emperor Jimmu in 660 BC. ''Kōki'' emphasizes the long history of Japan and the Imperial dynas ...

calendar, or 1944 in the

Gregorian calendar The Gregorian calendar is the calendar used in most parts of the world. It was introduced in October 1582 by Pope Gregory XIII as a modification of, and replacement for, the Julian calendar. The principal change was to space leap years dif ...

.War Department TM-E-30-480 ''Handbook on Japanese Military Forces'' September 1944 p 400 Due to the lack of raw materials available and the great damage by air raids to its industrial infrastructure, only 70 units were made. These units were retained for defense of the Japanese home islands during

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 vast majority of the world's countries—including all of the great powers—forming two opposin ...

History and development

In 1927, the

Bofors AB Bofors ( , , ) is a former Swedish arms manufacturer which today is part of the British arms concern BAE Systems. The name has been associated with the iron industry and artillery manufacturing for more than 350 years. History Located in ...

company of Sweden had designed a new 75 mm AA gun which was purchased by the

Royal Swedish Navy The Swedish Navy ( sv, Svenska marinen) is the naval branch of the Swedish Armed Forces. It is composed of surface and submarine naval units – the Fleet () – as well as marine units, the Amphibious Corps (). In Swedish, vessels of ...

. This was developed into a mobile anti-aircraft gun with a carriage which had wheels, and was exported to the

Republic of China Taiwan, officially the Republic of China (ROC), is a country in East Asia, at the junction of the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the northeast ...

Persia Iran, officially the Islamic Republic of Iran, and also called Persia, is a country located in Western Asia. It is bordered by Iraq and Turkey to the west, by Azerbaijan and Armenia to the northwest, by the Caspian Sea and Turkmeni ...

, and

Thailand Thailand ( ), historically known as Siam () and officially the Kingdom of Thailand, is a country in Southeast Asia, located at the centre of the Indochinese Peninsula, spanning , with a population of almost 70 million. The country is bo ...

. Japanese forces captured examples of the Bofors M29 75mm AA gun from the

National Revolutionary Army The National Revolutionary Army (NRA; ), sometimes shortened to Revolutionary Army () before 1928, and as National Army () after 1928, was the military arm of the Kuomintang (KMT, or the Chinese Nationalist Party) from 1925 until 1947 in China ...

of the

Kuomintang The Kuomintang (KMT), also referred to as the Guomindang (GMD), the Nationalist Party of China (NPC) or the Chinese Nationalist Party (CNP), is a major political party in the Republic of China, initially on the Chinese mainland and in Tai ...

government of China, and the Army Technical Bureau was impressed with its performance, which was much superior to the existing Japanese

Type 88 75 mm AA Gun The was an anti-aircraft gun used by the Imperial Japanese Army during the Second Sino-Japanese War and World War II. The Type 88 number was designated for the year the gun was accepted, 2588 in the Japanese imperial year calendar, or 1928 in th ...

. By

reverse engineering Reverse engineering (also known as backwards engineering or back engineering) is a process or method through which one attempts to understand through deductive reasoning how a previously made device, process, system, or piece of software accompli ...

a close copy was designed and went into production in 1943. However, Japan lacked the raw materials and its industrial infrastructure was too damaged by air raids to follow through with mass production. Only 70 units were completed before the

surrender of Japan The surrender of the Empire of Japan in World War II was announced by Emperor Hirohito on 15 August and formally signed on 2 September 1945, bringing the war's hostilities to a close. By the end of July 1945, the Imperial Japanese Navy ...

. The

Type 5 75 mm tank gun The ''Type 5 75 mm tank gun'' was used as the main armament of the Imperial Japanese Army prototype Type 4 Chi-To medium tank. It was one of the largest tank guns to be fitted on a World War II Japanese tank. Due to late war shortage-induced d ...

was a variant design of the Type 4 75 mm AA gun used as the main armament on the

Type 4 Chi-To The ("Imperial Year 2604 Medium Tank Model 7") was one of several medium tanks developed by the Imperial Japanese Army towards the end of World War II. While by far the most advanced Japanese wartime tank to reach production, industrial and mate ...

medium tank A medium tank is a classification of tanks, particularly prevalent during World War II which represented a compromise between the mobility oriented light tanks and the armour and armament oriented heavy tanks. A medium tank's classification is ...

Design

The Type 4 75 mm AA gun had a single piece

gun barrel A gun barrel is a crucial part of gun-type weapons such as small firearms, artillery pieces, and air guns. It is the straight shooting tube, usually made of rigid high-strength metal, through which a contained rapid expansion of high-pressure ...

with sliding

breech Breech may refer to: * Breech (firearms), the opening at the rear of a gun barrel where the cartridge is inserted in a breech-loading weapon * breech, the lower part of a pulley block * breech, the penetration of a boiler where exhaust gases leav ...

, mounted on a central pedestal. The firing platform was supported by four legs, each of which had adjustable screwed foot for leveling.

Combat record

Coming into service towards the end of the war, all seventy Type 4s that were operational were retained on the home islands as part of the bolstering of Japan's defenses against Allied air raids and against the perceived threat of

Allied invasion An alliance is a relationship among people, groups, or states that have joined together for mutual benefit or to achieve some common purpose, whether or not explicit agreement has been worked out among them. Members of an alliance are called ...

.MacLean. ''Japanese Artillery; Weapons and Tactics''

Notes

References

* Bishop, Chris (eds). ''The Encyclopedia of Weapons of World War II'', Barnes & Nobel, 1998. . * Chant, Chris. ''Artillery of World War II'', Zenith Press, 2001. . * McLean, Donald B. ''Japanese Artillery: Weapons and Tactics'', Wickenburg, Ariz.: Normount Technical Publications, 1973. . * Tomczyk, Andrzej. ''Japanese Armor Vol. 4''. AJ Press, 2005. . * US Department of War, ''TM 30-480, Handbook on Japanese Military Forces'', Louisiana State University Press, 1994. . * War Department TM-E-30-480 ''Handbook on Japanese Military Forces'' September 1944

External links

Taki's Imperial Japanese Army
{{DEFAULTSORT:Type 4 75 Mm Aa Gun Artillery of Japan 75 mm artillery World War II anti-aircraft guns 4 4 Weapons and ammunition introduced in 1944