"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"