by lieutenant colonel Velichko
Synopsis from:The articles reports experience acquired by 50 Guards Heavy Tank Regiment in a 600 km long offensive marsh made in cooperation with medium tanks (summer 44)
The manual [battle manual of armored troops] provides an average speed of tank columns equal to 10-12 km/h. The experience of a 600-km long marsh demonstrated that the average speed of heavy tanks [IS-2s] was 5-6 km/h or on half of the medium tanks’ speed. That speed is determined by the following reasons:
According to tactical instructions and battle experience heavy tanks operate behind medium tanks in combat. Hence heavy tanks are usually placed behind medium tanks in a tank column. They would face problems maintaining the same speed as medium tanks, since road pavement is damaged by tanks that passed before them. Another instance occurred when a forward detachment that included heavy tanks had to cross a small river near N. Medium tanks forded it without problems. However they smashed the soil of river banks so much that heavy tanks had to wait until it was reinforced by engineers. As a result the crossing took much longer than it would be if heavy tanks moved by a separate column. And such small rivers were numerous, so heavy tanks had to spend much more efforts than medium tanks that went along the same road before them.
The second reason is that heavy tanks require more maintenance especially on sandy or dusty roads. Practical experience demonstrated that manuals and instruction give only minimal requirements of maintenance. The first halt on a march must be made after 30 minutes instead of 1 hour according to manuals, and it must be not shorter than 30 minutes. On sandy and dusty roads subsequent halts must be made every 2 hours about 1.5-2 hour long. That is determined by time needed to clean air filters (50-60 minutes), and when moving on dusty roads filters should be cleaned at least every 2 hours. Only in absence of dust one can keep to manual provisions. There are other reasons that can lead to a breakdown of a heavy tank before its guaranteed term expires, whereas in case of properly organized maintenance it could operate 50% longer than the guaranteed term. Hence a need to give crews enough time for maintenance, which is easy to make when heavy tank move by a separate column, but problematic when they make marsh together with medium tanks. It should be also remembered that the tank column needs some time (10-15 minutes) to halt, align and mask tanks at halt.
Therefore, the place of heavy tanks in a column, terrain broken by medium tanks, and large maintenance requirements of heavy tanks are principal reasons that limit operational speed of heavy tanks to 5-6 km/h.
Place of heavy tanks in battle formations of an armored unit [tank corps].
Two principal options:
1. Heavy tanks are distributed by a column (reinforce the forward detachment, the main forces, and part of theme is kept in reserve) – see Scheme 1.
2. Heavy tanks operate as a separate column as a reserve of superior commander.
The first option is expedient in entering breakthrough when enemy armored counterattacks are imminent. Example: a group of heavy tanks reinforced a tank battalion operating as a forward detachment. When the detachment reached S. they met a group of enemy which included tanks and SP guns and offered strong resistance. Two medium tanks were set on fire. Heavy tanks quickly took positions and knocked out two enemy assault guns, the rest were forced to retreat. Availability of heavy tanks allowed the forward detachment to carry out its task relatively easily. Conclusion: a battle formation with heavy tanks distributed by a column with about 50% of them in reserve proved efficient in practice.
The positive sides of employing heavy tanks as a separate column are:
- Superior commander can employ heavy tanks in mass and concentrate them in a critical place
- In a separate column heavy tanks can move without making frequent short halts which is one of the main factors limiting their operational speed.
- Heavy tanks can receive requisite maintenance.
Therefore, a march in a separate column demands less efforts of crews and average operational speed increases to the same values as for medium tanks.
Movement in a separate column brings the lifetime of heavy tanks to the maximum.
It is expedient to break up heavy tanks by a common column when encounters with enemy tanks or SP guns is expected and terrain limits maneuver of tanks. When there is little probability to meet enemy armor it would be more efficient to have heavy tanks as a reserve in a separate column.
(articles on war experience of the 50 Guards Heavy Tank Regiment)
Bottom line: IS tanks had problems maintaining the same tempo as T-34 and required more time for maintenance.