Monday 16 December 2019

IS Debut

"Military Council of Armoured and Mechanized Forces of the Red Army

April 1st, 1944

To commander of the 2nd Ukrainian Front, Marshal of the Soviet Union, comrade Konev

The regiments of heavy IS tanks and ISU-152 SPGs consist of the first tanks and SPGs of this type. As tanks and SPGs of the first production batch, they have a number of minor technical drawbacks, as there is not yet sufficient experience in their use. I ask you to take measures and offer assistance in the matters of studying these vehicles in battle, discovery of their usage and technical drawbacks, and study of the best way to use them in battle.

IS tanks and ISU SPGs are mainly designed for fighting enemy heavy tanks and SPGs, artillery, pillboxes, and dugouts deep within enemy defensive lines. Heavy tank regiments, like others, must chiefly be used within tank and mechanized corps.

Until the enemy is encountered, their place is in the second echelon. They must be protected by medium tanks from the flanks and every tank or SPG must be protected from tank destroyer groups by a submachinegunner squad. A company of SMG squads is included in the TO&E of the regiments with the ratio of 5 men per tank or SPG.

When the regiments are put into action, it is desirable to apply them on terrain that is most advantageous for tanks and can be navigated without excess pressure. Take all measures to ensure that these tanks do not fall into the hands of the enemy.

Take into account that these regiments do not have organic reconnaissance elements. As a rule, units that fight with them must supply them with reconnaissance.

Tanks equipped with 122 mm guns and SPGs equipped with 152 mm guns as a rule fire from standstill, short stops, or ambushes from 1.5-2 km. Tanks armed with 85 mm guns fire from 1.2-1.5 km. 

As tanks equipped with 122 mm guns and SPGs equipped with 152 mm guns carry a limited amount of ammunition, it is necessary to organize timely supplies in battle and ensure that ammunition is expended wisely.

I especially ask you to provide the units due time to perform technical service and correction of defects.

Lieutenant General comrade Taranovich and a group of officers have been dispatched to study these tanks and SPGs to establish their value in battle. I ask you to offer them assistance.

Inform me of any notes regarding the advantages and drawbacks of IS tanks and ISU SPGs.

Commander of Armoured and Motorized Forces, Marshal of Armoured Forces Fedorenko
Member of the Military Council, Lieutenant General of the Technical Forces, N. Biryukov"


  1. "tank destroyer groups" refers to Infantry with AT equipment, right? I can't imagine submachinegunners to be of much use against a Stug or Jpz. IV.

    1. Yes, these would be infantry with anti-tank grenades and similar equipment. The submachinegunners aren't there to shoot at the StuG, they're there to shoot at the enemy infantry that StuG is supporting.

  2. Once again we have a document that instructs IS-2 and ISU-152 crews to engage at ranges (1500-2000 meters) that some insist a) they could not hit accurately and b) that they would not penetrate many kinds of enemy armored vehicles even if they did hit. Moreover, the article also admonishes the same crews that their ammo supply is limited so the assumption obviously is that it won't take a lot of repeated tries to get a hit at that range.

    What's even more interesting, is the advice given to those firing 85 mm guns, to engage at 1-1.2 km. I say that because many of the same people also say the 85 mm gun was worse than the Pak40 and would be struggling to penetrate even a Stug (a very common opponent) at that distance.

    This and more lead me to doubt a lot of published penetration values, at least in the transliteration of Russian values to US/British values. When Russian tests say "the 85 mm could penetrate the front of a Tiger I at 1000 meters" then I'd assume they're using Russian criteria for "penetration" which would be at least 25 % more by US/British metrics. But when Bird and Livingston say something like "105 mm at 10000 meters" then I'm head-scratching why it isn't more.

    1. British penetration values measure entirely different things and you get absurd results like nearly 90 mm of penetration for the short M2 75 mm gun. These values absolute cannot be compared to each other. Interestingly enough, the curves are very similar when transposed:

    2. Peter, your curve for the British 6-pounder matches what I expect--the curves were similar, but there's like a 25-30 % absolute difference between the individual points on the two graphs. So when the Soviets say the 85 mm penetrates 100 mm of armor plate at 1000 meters by their tests and calculations and moreover the same gun penetrates the same 100 mm on a Tiger I, I'd expect the translated US/British values for the 85 mm to have a similar curve, but should be in the 125-130 mm range. Not 107 or 105 mm which is only a little difference, and saying that the US/British and Soviet penetration criteria are about equally demanding, which they were definitely not.

    3. Correct, British penetration requirements only require that the armour have a hole in it, not that the shell ends up on the other side of the plate.

    4. The penetration could be at those ranges at 0̊. But, not at 30̊. So when one doesn't have a good angle on a target it might not make sense to open fire until a better range is achieved. Also, the 1944 Soviet range tables for the 122mm were a bit off so might be optimistic at those long ranges.