By August of 1942, when the newest heavy Tiger tank just entered the army, German high command already demanded a new, heavier and more powerful, vehicle. In the fall of the same year, Erwin Aders of Henschel and Ferdinand Porsche started building the new vehicle.
Each engineer approached the problem differently. Porsche didn't get very creative. He took his VK 45.01 (P), also known as the Porsche Tiger, and performed a series of changes, which were closer to cosmetic than functional. The VK 45.02 (P) received the same electric transmission as its predecessor, a similar twin gasoline Simmering-Graz-Pauker engine, 200 hp each, and the same six paired individual road wheels. The hull was changed by adding sloped armour, as well as the turret, which had to be changed for the new 88 mm KwK 43 gun. Porsche made two types of tank: one with a front turret, and one with a rear one.
Aders' project was closer to what was actually requested. In part, this was maximum parts commonality with the currently developed Panther II. Aders' heavy tank ended up preserving the Panther's proportions, with with thicker armour. The front plate was 150 mm thick, positioned at 50 degrees. 80 mm thick side armour was positioned at 25 degrees. The suspension, made of 10 paired road wheels, was partially borrowed from the Tiger, and partially from the Panther. The tank received a 700 hp Maybach engine and a cooling system made of four radiatiors, left and right of the engine. The gun mantlet and hull machine gun mounts were the same as on the Panther II.
Porsche considered the tender to be his, and ordered 50 turrets at the Krupp factories in Hessen. When the competition arrived, Hitler's sympathies lay with Henschel's creation. Porsche's project was declined due to an unreliable suspension, unreliable transmission, and a high use of deficit materials, such as copper.
Ironically, this is the second time when Porsche's project was declined, and later used elsewhere. The 50 turrets ordered from Krupp were installed on the first 50 Tiger IIs.
The Tiger II started production in January of 1944. Despite deficits and a rapidly worsening situation, German high command had grandiose plans for this tank. 120 vehicles were to be built per month, 1237 in total. British aviation corrected those plans by bombing Kassel. As a result of this, only 20 tanks were built by May of 1944.
The first combat experience showed that the tank needed more work. Porsche's turret resulted in a large chance to send a shell ricocheting into the thin roof armour. Krupp had to design a new turret with a vertical front, to eliminate the chance of a ricochet. The thickness of the front turret armour was increased to 180 mm. The turret was also larger, increasing the ammunition capacity from 77 to 84 shells.
Aside from the turret, many small changes were made. The gun was improved, a new gun sight was installed, the engine compartment armour was improved. In November of 1944, the tanks received new tracks. In March of 1945, a device to clear the barrel of gases was put into production. It did not need a compressor, and used air compressed by the gun's recoil.
The closer the end of the war was, the harder it was to build tanks. Along with the modernizations, the tanks were simplified. Latest vehicles were not even painted on the inside. There was no time, they were needed on the battlefield.
Tiger IIs were used in heavy tank battalions, replacing Tiger Is. No new units were created for them. Usually, the replacement happened this way: battalions were recalled, arrived to the training facility at Ohrdruf or Paderborn, received their new tank, went through training, and returned to the front.
On the Western Front, the only tanks capable of combating the Tiger II were the Sherman Firefly, Challenger, Archer, Achilles, and, after September of 1944, M36 Slugger tank destroyers. Tiger IIs also suffered heavy losses from Allied aviation.
On the Eastern Front, the tank made its debut at the Sandomir foothold, during an attack of the Polish city of Staszow. In the battle, "King Tigers" of the 503rd heavy tank battalion were ambushed by the 53rd tank brigade and its assigned artillery. As a result, 24 Tiger IIs were knocked out by Soviet sources, and 11 by German. [I don't know what sources they are looking at, strategic maps of the area and memoirs from the Soviet side account for 13 Tiger II tanks knocked out] Three tanks were captured intact and delivered to the Kubinka proving grounds.
There is a legend that either Porsche himself or his son was killed at Staszow. The highlight of the story is that the man put so much faith into the invincibility of his tank, that he rode it into battle. In reality, Porsche was not the creator of the tanks at Staszow (some of the turrets were new, Henschel ones). If you're not feeling too lazy, you can check the dates of death of Dr. Porsche and his son. He died in 1951, and his son lived until 1998.
Despite the menacing armour and gun of the tank, it had many drawbacks. The "King Tiger" was very unreliable. Vehicles broke down after a very short march. Heavy tank battalions often went into battle with reduced numbers because of this. The worst part was the suspension. The tracks often jammed, drive wheels lasted only 300 hours. The side reductors were destroyed after only 250 hours of use. The overloaded engine overheated, the cooling system could not keep up. Finally, the tank was so heavy, that few bridges could hold it. This significantly reduced the operational maneuverability of the "King Tiger". By the end of the war, the Germans could no longer manufacture quality armour, so the tank's thick hide could not protect it from shells as well as earlier vehicles. Even on non-penetrating shots, fragments of armour flew off and struck the crew and components.
Overall, the Tiger II's characteristics were inferior to both its predecessor, and the Ferdinand tank destroyer. Theoretically, it could defeat any Allied tank. Realistically, it had no such ability. Soviet forces could easily outmaneuver it, hitting the sides or rear. The Allies relied on aviation, relentlessly bombing the German tank positions. There is evidence of 2100 airplanes that were readied to attack the 503rd heavy tank battalion.
In total, you could say that the Tiger II was one of the strongest tanks of WWII. However, the small numbers, many defects in its construction, and effective combat of Soviet and Allied troops prevented it from having an effect on the status of the fronts.
Today, at least nine "King Tigers" survive. In Russia, an example of this fascinating fighting machine can be seen at Kubinka.
Original article available here.