Type 3 Chi-Nu medium tank
The Type 3 Chi-Nu was a medium tank developed and produced by the Imperial Japanese Army during the final stages of World War II, representing Japan's last major tank design to enter service. Based on the chassis of the earlier Type 1 Chi-He medium tank, it mounted a powerful 75 mm Type 3 tank gun in a redesigned turret, with production totaling 144–166 units between 1944 and 1945, primarily for defensive operations on the Japanese home islands.[1][2] Development of the Chi-Nu began in 1943, driven by the need to counter the superior firepower and armor of Allied tanks like the American M4 Sherman, following Japanese experiences in battles such as Khalkhin Gol in 1939 and the Burma campaign in 1942.[2] The design retained the Type 1's Mitsubishi Type 100 V-12 diesel engine producing 240 horsepower, achieving a top speed of approximately 39 km/h and a range of 210 km, while weighing 18-18.8 tons with dimensions of 5.73 m long, 2.33 m wide, and 2.61 m high.[1][3] Its armor was improved over predecessors, featuring up to 50 mm on the hull front and turret, though sides and rear remained thinner at 20-25 mm, operated by a crew of five.[2] Armament included the main 75 mm L/38 gun capable of penetrating 90 mm of armor at 100 m, supplemented by one or two 7.7 mm Type 97 machine guns for secondary defense.[1] Despite its potential as a capable medium tank comparable in role to the Sherman or T-34-85, the Chi-Nu saw no combat, as it was reserved for units like the 1st and 4th Armored Divisions and various independent tank brigades preparing for an anticipated Allied invasion of Japan that never materialized.[3] Production was limited by severe resource shortages, with steel prioritized for naval construction, resulting in only 55 units completed in 1944 and the remainder in 1945 before Japan's surrender.[2]Development
Background and requirements
By the early 1940s, the Imperial Japanese Army faced significant challenges in armored warfare due to the limitations of its existing tank designs against increasingly capable Allied vehicles. The Type 97 Chi-Ha medium tank, the mainstay of Japanese armored forces since 1937, was armed with a short-barreled 57 mm gun that lacked the penetration power to effectively engage American M4 Sherman tanks at combat ranges, as demonstrated in battles such as those in Burma in 1942.[2] This inadequacy was exacerbated by earlier defeats, including the 1939 Battle of Khalkhin Gol against Soviet forces, which underscored the need for tanks with superior anti-tank capabilities beyond mere infantry support roles.[2] In response to these shortcomings, the Japanese Army initiated a program in 1943 to develop a new medium tank as a stopgap solution to counter the Sherman, prioritizing firepower over comprehensive redesign. The primary requirement was a main armament capable of defeating the Sherman's 50-75 mm frontal armor at distances up to 500 meters, leading to the adaptation of the Type 3 75 mm tank gun, a modified version of the Type 90 field gun for vehicle mounting.[2] Development work began in May 1943 under the oversight of the Sagami Army Arsenal, aiming for a vehicle weighing around 18 tons with balanced mobility for scouting and infantry accompaniment in defensive operations.[2] The design drew on the chassis of the earlier Type 1 Chi-He medium tank but required a larger turret to house the new gun, reflecting a focus on rapid production using existing components amid resource constraints. Foreign influences shaped these requirements, as Japanese military attachés in Berlin provided reports on advanced Axis designs like the German Panther and Tiger tanks, alongside intelligence on Soviet T-34 and U.S. Sherman tanks, emphasizing the need for sloped armor and high-velocity guns.[2] The Chi-Nu was envisioned to serve in anticipated homeland defenses against Allied invasions, with specifications calling for a crew of five, a top speed of 40 km/h, and armor up to 50 mm thick on the hull front to provide adequate protection without excessive weight.[2][1] This urgent project was approved for production in October 1943, though it remained an interim measure until heavier tanks like the Type 4 Chi-To could be fielded.[2]Design process and production
The development of the Type 3 Chi-Nu medium tank was initiated by the Imperial Japanese Army in May 1943 as an urgent response to the shortcomings of existing Japanese tanks against the American M4 Sherman, particularly the inadequacy of the 47 mm gun on the Type 97 Chi-Ha Kai variant in penetrating its armor.[2][4] The design team, under the oversight of the IJA's technical headquarters, adapted the chassis from the earlier Type 1 Chi-He medium tank, which itself was a simplified evolution of the Type 97 Chi-Ha with enhanced armor and a more powerful engine, to serve as a stopgap solution until the more advanced Type 4 Chi-To could enter production.[2][1] A key innovation in the design process was the creation of a new large hexagonal turret to accommodate the 75 mm Type 3 tank gun, derived from the 75 mm Type 90 field gun originally based on a Schneider design, providing significantly improved anti-tank capabilities with penetration of up to 90 mm of armor at 100 meters.[4][1] The hull retained the Type 1 Chi-He configuration, including its running gear, while the overall weight increased to approximately 18.5 tons.[2] Design work was completed by October 1943, and the prototype was accepted for service later that year, with Mitsubishi Heavy Industries selected as the primary manufacturer due to its experience with previous Chi-series tanks.[2][4] Production faced severe constraints from Japan's wartime resource shortages, particularly in steel, which was prioritized for naval construction amid escalating Allied naval superiority in the Pacific.[2] Manufacturing began in September 1944 at Mitsubishi's facilities, with 55 units completed that year; an additional 111 units followed in 1945 before Japan's surrender in August, bringing the total to 166 tanks based on most records, though some sources cite lower figures due to incomplete documentation.[2][1][4] The limited output reflected broader industrial challenges, including Allied bombing campaigns that disrupted factory operations.[4]Technical specifications
Protection features
The Type 3 Chi-Nu medium tank's protection relied primarily on its steel armor plating, which represented an upgrade over the thinner armor of predecessors like the Type 97 Chi-Ha, utilizing a modified chassis from the Type 1 Chi-He for enhanced durability.[1] The armor was constructed from rolled homogeneous steel plates joined by welding, a departure from the riveted designs of earlier Japanese tanks, allowing for a more robust and less brittle structure.[5] The hull armor emphasized frontal protection, with a vertical 50 mm plate on the glacis to resist direct hits from medium-caliber anti-tank rounds. Sides measured 25 mm, providing coverage behind the suspension components, while the rear was 20 mm thick; the upper hull roof and lower belly plates were thinner at 12 mm and 8 mm, respectively, to balance weight and mobility.[5][1] The turret, a hexagonal welded design, featured 50 mm frontal armor, including a prominent gun mantlet, with forward sides at 35 mm tapering to 25 mm on the rear sides and rear face for adequate all-around defense. The turret roof was 10 mm thick. An additional armored tray protected the recoil brake cylinders on the turret front, mitigating vulnerabilities in the gun mounting area.[5]| Component | Front (mm) | Side (mm) | Rear (mm) | Roof/Bottom (mm) |
|---|---|---|---|---|
| Hull | 50 | 25 | 20 | 12 / 8 |
| Turret | 50 | 25–35 | 25 | 10 |