At the beginning stage of Pacific War, Type 97 Chi-Ha and Type 95 Ha-Go (light tank) were the backbone of the Imperial Japanese Army. As the war progressed, these tanks started to face significant challenges posed by Allied tanks. In Burma Campaign and Philippines Campaign, the firepower of 57 mm cannon mounted on Type 97 was proven to be insufficient against Allied tanks. Imperial Japanese Army therefore developed Type 1 47 mm tank cannon which had higher armor penetrating power. This cannon was later mounted on Type 97 Chi-Ha and Type 1 Chi-He Medium Tanks. The arrival of new tank cannons made it possible for Japanese armored forces to stand against Allied tanks.
At the later stage of the war, large numbers of American M4 Sherman tanks arrived at the front line and put new pressure on Japanese armored forces. The Imperial General Headquarters (Daihon'ei) decided to develop a new tank to counter the enemy threat as well as a replacement for Type 97 and Type 95.
The Army Technical Bureau had been working on the Type 4 Chi-To medium tank as the counter to the M4 Sherman, but there were problems and delays in the program. As a result a stopgap tank was required. The Type 3 medium tank Chi-Nu was developed to cope with the M4 Sherman. Work on the Type 3 Chi-Nu started in May 1943 and was finished by October, just six months later. The low priority given to tank production by 1943 meant that the Type 3 did not actually enter production until 1944, by which time raw materials were in very short supply, and much of Japan's industrial infrastructure had been destroyed by American strategic bombing.
A total of 144 units were produced (55 units in 1944, 89 units in 1945). The Type 3 Chi-Nu was the last tank that was fielded by the Imperial Japanese armed forces, and was still being produced at the end of the war.
Armor and Protection
The Type 3 Chi-Nu retained the same chassis and suspension of the Type 97 but with a large new hexagonal gun turret and a commander's cupola. It was the last design that based directly on Type 97 lineage. The hull of the tank resembled the hull of Type 1 Chi-He but with an enlarged turret ring to fit the new turret.
The Chi-Nu used a lever system rather than a handle system. It also had the same engine as the Chi-He, producing 240 hp and gave the tank a top speed of 38.8 Kph.
The main armament of the Type 3 Chi-Nu was the 75 mm caliber Type 3 Tank Gun. The gun could be elevated between -10 and +25 degrees. Firing a shell at a muzzle velocity of 680 metres per second (2,200 ft/s) it gave an armor penetration of 90 mm (3.5 in) at 100 m (110 yd) and 65 mm (2.6 in) at 1,000 m (1,100 yd).