Now that I'm thinking ASL after a 2-3 month hiatus, I will do a few posts about things that have been rattling around in my skull.
I'll start with a short and easy one, to ease me back into the saddle.
In any such posts I'll only deal with significant combat units, ignoring supply, medical, etc.
Soviet Heavy Tank organisations.
At the start of Barbarossa the Soviets had Tank Corps with 2 Tank divisions and a Motorised Division. These were true Corps sized units unlike the 42+ Tank/Mechanised Corps which where really divisional in size.
Each Tank Division had 2 Tank Regiments each with a HQ, Recon Co., 1 Heavy Tank Battalion, 2 Medium Tank Battalions, a FT Tank battalion and maintenance and supply companies.
The Heavy battalion had a HQ of 1 KV-1, 3 BA-10/20 AC, 3 companies each HQ 1 KV-1 and 3 Platoons each 3 KV-1 for a total of 31 KV-1 and 3 AC. In theory! KV numbers did not match requirements so T-28 might be seen.
By mid July the Tank Corps disappeared and a reduced Tank Division with 2 Tank Regiments was official. The Tank Regt had 1 medium and 2 light tank battalions. The medium battalion had 1 heavy company (as above with 1+3x3 KV) and 2 medium companies. The divisional KV total dropped from 63 to 20 KV.
By August the main tank unit was the Tank Brigade with a medium battalion and 2 light battalions. The medium company had 2 medium companies and 1 heavy company with 7 KV. I've never read whether the KV co. had 1 HQ and 2 platoons of 3 KV or 3 platoons of 2 KV, however reading about Katukov's action at Mtsensk mentions him ordering 3 KV to a new position, so I suspect 1 KV in HQ and 2 platoons of 3 KV.
The December '41 Tank Brigade had 2 tank battalions each with a heavy, a medium and a light company. The heavy company was now down to HQ 1 KV and 2 platoons of 2 for a total of 5. This remained the standard heavy tank company size, a platoon in any other army.
By July '42 heavy tanks were dropped from Tank Brigades and heavy tanks were organised in separate guards heavy breakthrough regiments by October '42. Each such regiment had 1 KV in HQ and 4 companies each with 5 KV (1+2x2) for a total of 21. By early '44 a SMG company and pioneer platoon were added.
The final step was to combine 3 such regiments into a heavy tank brigade that had a SMG battalion and a total of 65 IS-2.
So at the ASL level, heavy tanks (T-28, T-35, KV, IS) went from 10 per company (1+3x3) to 7 (1+2x3) to finally 5 (1+2x2) by the end of '41.