40M Turán I was a Hungarian tank of World War II - a total of 424 were made in two variants: Turan I with a 40 mm gun and Turan II with a 75 mm gun. It was based on the design of the Czechoslovak Škoda T-21 medium tank prototype.

In December 1937 the Škoda workshops prepared a prototype of a medium tank based on the earlier successful LT vz. 35 project. Two prototypes were started and designated S-IIc, but their construction was never finished. The tank weighed 16.5 tonnes (16.2 long tons; 18.2 short tons), was armed with a 47 mm Škoda A9 vz. 38 gun, two 7.92 mm machine guns and its maximum armour was extended to 30 mm. Finally, the S-II-c was to have a better 13.8 liters engine giving 250 hp; this increased the maximum speed to roughly 50 km/h.

After Germany annexed Czechoslovakia, the prototypes were finished under the new designation of T-21, which in turn was a predecessor of a new prototype; the T-22. Two of the latter type were given to Hungary in 1941. The Hungarian engineers further extended the front armour to 50 mm and replaced the 47 mm gun with a 40 mm Škoda A17. The overall weight was also increased to over 18 tonnes.

The Turan was produced in several versions. The Turan I was the original medium tank type, which mounted the 40 mm gun.[1] The gun, the standard Hungarian light anti-tank gun, could fire the same ammunition as the Bofors 40 mm anti-aircraft gun. The gun was mounted in a riveted turret. A total of 285 tanks were produced between 1941 and 1944.

After the disastrous Stalingrad offensive, the army realized that they needed a more powerful weapon to counter the more effective Soviet tanks, especially the T-34. A variant was ordered which utilized a short 75 mm gun in an enlarged turret. Known as the 41M Turan II, this vehicle otherwise remained virtually unchanged from the original vehicle. Despite the improvement, the relatively low velocity of the projectile was unable to pierce the frontal armor of a T-34, except at point blank range. The T-34's main gun could penetrate the Turan's 50 mm of armor at a much greater distance. Hungarian manufacturers built a total of 139 vehicles in 1943 and 1944 before the Soviet occupation of Hungary.

Aside from tank production, the chassis was the basis for the Zrinyi II assault gun. This mounted a 105 mm short gun in the hull, and lacked the traversable turret of a tank. Only 60 examples of this vehicle were produced. The only other vehicles known based on this chassis were the Turan III and the Zrinyi I, both of which used the German 75 mm L43 tank gun (which armed some variants of the German Panzer IV medium tank). Both vehicles were produced as prototypes only, as the Hungarian Army were supplied with German armored vehicles.

The Turan was employed by the 1st and 2nd Hungarian Armored Divisions, as well as the 1st Cavalry Division, in 1943 and 1944. Both types were hopelessly outclassed by the Soviet's superior T-34 and IS-2 tanks. The vehicle's combat début was not until April 1944 in Galicia with the 2nd Armored, during which that division lost a quarter of their tanks and failed to achieve their objectives, mostly due to the inadequacies of the Turans.