The Pz.kpfw VI Tiger II Ausf. B "KingTiger" VK4503(H) was the most powerful combat tank of WWII. Up to the end of the war, the Allies did not introduce anything that could effectively counter it. The Tiger II combined a powerful and effective gun with armor that was virtually impervious to any Allied tank or anti-tank gun. Planning for the Tiger II started as early as May 1941, a year before the Tiger I entered production. By the fall of 1942/January 1943, designers started work on a new heavy tank that would eventually replace the Tiger I. In January 1943, Hitler ordered the new Tiger to be armed with a long 88mm gun and have 150mm frontal armor and 80mm side armor.