The Pz.kpfw VI Tiger II Ausf. B KingTiger" VK4503(H) was the most powerful combat tank of World War II. 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.