The Tiger was one of the German responses to the appearance of new Soviet tanks in 1941 and in particular of the T-34. At the time the German Army had no heavy tanks, except for a few experimental vehicles. However, once the new Russian tanks were encountered the German High Command realised the need for tanks more powerful than the existing Pz.Kpfw.IV. In consequence two new tanks were hurriedly developed. One was the 56 ton Tiger, whose design incorporated some features of one of the earlier experimental tanks but which was armed with a tank version of the 88mm anti-aircraft gun that had already proved highly effective as an anti-tank weapon. The other was a new medium tank which became the Panther, a 43 ton vehicle armed with a 70 calibre long, high velocity 75mm gun. The Panther began to be produced in January 1943 and, together with the Tiger, gave the German tank units a qualitative superiority over the Russian tank units. But both tanks were produced on a relatively small scale, the total production of the original Tiger I amounting to 1354 and that of the Panthers to 5976 (1.75). In consequence, there were not enough Panthers to reequip the Panzer divisions completely with them and the Tigers were generally held back in independent battalions. Both tanks had the same general layout as Pz.Kpfw.IV and five-man crews but apart from having much more powerful armament and thicker armour they were much more advanced mechanically. As a result of its combination of characteristics the Panther came to be regarded as the best medium tank of the 1943-45 period while the second version of the Tiger became the most powerful tank to be used during the Second World War. Thus, Tiger II was armed with a higher performance 88mm gun which was 71 calibres long and which could pierce considerably thicker armour than the 122mm gun of the IS-2. It was also heavily armoured, its frontal hull armour being 150mm thick, although this contributed to its weight of 68 tons, which made it the heaviest tank used during the war. But the total production of Tiger II amounted to only 489 vehicles. In the meantime, while the Tiger and the Panther were being developed, the existing German tanks were belatedly armed with more powerful guns. In particular, Pz.Kpfw.IV was armed in 1942 with more powerful 75mm guns, first 43 and then 48 calibres long, instead of the short barrelled gun of 24 calibres, which had been used in German tanks since the Grosstraktoren of 1929. New designs and improved versions of the existing vehicles developed in response to the appearance of the T-34 and KV not only made German tanks more than a match for the Soviet tanks in terms of gun-power but also put them well ahead of British and US tanks.