Historical Question: Pz III/IV

[Mashsmouth]

I wonder, what was the logic behind making the less armored Panzer III to be used for against enemy tanks and the more armored IV for infantry support? Yes, it was flipped during the war, after experience, but what logic made them designated for their wrong roles in the first place?

[Surtur]

I am no WW2 historian, but this is my basic understanding, I am sure someone else can correct me where I am wrong ;)

The idea of having tanks engaging tanks was something rather new at the time.

The tanks were originally designed to break through heavy fortified lines. As such, you would need relatively heavy tanks in order have enough power to do so. In addition, the rounds fired were often exploding rounds to deal with entrenched infantry, rather than armor penetrating rounds. A good example here is the French Renault Bis.

These tanks were well armoured, since they would take a punch advancing on entrentched positions and they were allowed to be relatively slow, since they moved up at the same speed as the infantry.

The lighter tanks, such as the Panzer III or the French Sumoa S35 were lighter because they needed more speed to be able to operate exploiting gaps in the enemy line. When it became known that the PzIII did not pack a big enough punch, the temporary solution was to reverse the roles.

[Kanone]

Maybe because of the main gun?

http://en.wikipedia.org/wiki/3.7_cm_KwK_36

http://en.wikipedia.org/wiki/7.5_cm_KwK_37

[Woody]

As the war progressed the chassis for each tank proved to better suited for a different task than what was conceived during the design and development.

The chassis on the IV's were better suited to carry larger guns and as the war progressed so did the size of guns and thickness of armor on tanks on both sides. Instead of redesigning and having to retool a plant it was more effient to use what they had and just change the roles the tanks served.

[cuqeen]

Infantry support tanks need large caliber guns to do damage to infantry and fortifications, so only the bigger tanks could carry the big guns with their ammo. At the start of WW2 anti-tank guns were small caliber and small tanks could carry them and their ammo. Anti-tank tanks should be as small as possible to be hard targets to enemy tanks and guns, so small tanks were better. All WW2 initial tanks had very weak armor, (only the Czech german tank was decent) so there was not much armor difference.
I think that later in WW2 Pz4 was the main anti-armor and inf support tank, i mean it was mainly used in both roles and Pz3 became less important and more obsolete and was used in special roles (command tank etc) and did not take Pz4 place.

[Mashsmouth]

Hmm. Thanks for the answers everyone, interesting.

I had assumed when you fight a tank --> get the biggest thing you can. Intesting what they did there.

[cuqeen]

Pz3 was too small to carry the 75mm infantry gun, only Pz4 was big to carry the gun and much ammo. Pz3 had 37mm gun first and finally got the 50mm long gun and with 3-men turret and radio was good for a while. But Pz3 never got the 75L pak40 anti-tank gun to continue the evolution and upgrade, Pz4 got that and Pz3 was very obsolete in 1943 as a medium main tank, the 50L gun could not penetrate many enemy tanks armor.
If you see the modern tanks today, tanks have 120mm+ guns with big ammo shells but designers try to create as much smaller and compact tanks as possible (and as fast as possible too). Huge and very heavy tanks (and ultra slow as old technology allowed) was a pre-WW2 concept, like the French huge tank that fought in 1940 and was considered a land battleship but was only a huge and slow target to enemy guns and aircrafts. Also the russians made some land fortress type tanks that had mostly awesome specs but their real life combat performance was not satisfactory.

[Rommel]

As far as I recall, the prevailing doctrine of the use of tank prior to World War II was to support infantry in achieving a breakthrough. Tanks are to be used to exploit a gap or fill it as the situation develops. Thus, Western armies (France, US, Britain, and to an extent USSR) designed tanks that fit within this doctrine. Tanks were classified as Infantry tanks (heavily armored, slower, but with a more powerful gun) or Cavalry (fast but with a weker cannon). Advances in radio communication (US, Germany) and doctrine (Germany) proved this doctrine deficient in achieving a breakthrough. Early German success (in 1939-41) with combined arms tactics proved that a doctrine that overwhelms an enemy's ability to react is fruitful. Advances in tank design emphasised a balance between firepower and protection can be achieved. An early example would be the T-34 (USSR). Later a heavy tank design (IS series in USSR, Pz.VI in Germany) were used to counter the effect of the common medium (balanced) tanks in the armies as far as technology then allows.