The average Red rifleman was sent to the front with no serious training, although there were some WWI veterans. Training was on the job.
With inexperienced troops, and often inexperienced commanders leading them, tactics tended to be simple. Communication was difficult, both because of the free-flowing nature of the war and a lack of technical equipment, so unit flags returned to the battlefield.
Lack of ammunition meant that combat was at much closer quarters than the weapons would suggest.
But this was the reality for almost all troops on almost all fronts of the war. The average Red unit was little different from the average Polish, Estonian or Latvian one, other than often having less motivation (manifested in the differing rates of desertion). The typical Red infantry unit was probably more motivated than many of the conscript White units of 1919 and 1920 though.
All Soviet foot were "rifles", although in the early period a few called themselves "infantry", and were grouped to make the larger units as homogenous as they could be. So "international" battalions were grouped into international regiments and international brigades, when possible, not spread out. Sometimes emergencies might cause brigades to be bundled together from disparate elements, but this was not the norm.
Divisions were numbered sequentially, although in the early period they might bear a geographic title as well when two units of the same number were generated, so the 21st RD was the 2nd Urals RD for a time. Many had unofficial titles as well. Only the Latvian and Estonian Divisions were officially outside this numbering system.
With a purely triangular system, the brigades and Regiments also ideally numbered sequentially. So the 1st RD would have the 1st to 3rd Rifle Brigades, made up of the 1st to 9th Rifle Regiments. The 57th RD would be the 169th, 170th and 171st RBs, and the 505th to 513th RRs. In practice it often didn't work out like that unless the division was recruited from scratch. Those formed from pre-existing units tended to keep their regimental numbers and names, at least for a while.
From June 1919, ignoring non-combat elements, a Rifle Division was made up of three rifle brigades, an artillery brigade, a cavalry regiment, an aviation detachment, an armoured detachment, a signal battalion and an engineer battalion, for a total of nearly 40,000 men. The previous structure, for wargames purposes, was identical.
In practice, this was never even close to observed. Mostly they had three brigades, but often one was tasked separately or added to another division, so it was common to see a KomDiv with two or four brigades. If a brigade took very heavy casualties, it might be disbanded entirely to fill out the other two in the division.
Rather than fill up their current divisions as it expanded, the Red Army chose to mostly recruit new ones. The ones at the front would be sent recruits irregularly and might recruit on the way, but were rarely pulled out for a complete restructure. A Rifle Division would generally in the field have from 4,000 to 12,000 men, no more than 50% of whom would be "bayonets". Divisions on the Eastern Front tended to be larger.
The integral cavalry is discussed in the section for the Red Cavalry. It rarely reached anything over 400 sabres.
The artillery brigade was meant to have five battalions (divizions) – three light, one howitzer and one heavy, plus three more light battalions at brigade level. In practice 30 guns was quite a lot for a division, although it could range from none to more than 50. There was no process of evening out across divisions, so the number of guns not particularly related to the overall size of the division. Most guns were 3-inch, as the Army commanders often took heavy guns for their reserve.
Some divisions did have an engineer battalion. As the war went on the armoured detachment was more likely to actually have some armoured cars.
The aviation was always fictional – such a scarce resource, even when it existed, was always going to be kept at Army or Front level.
A rifle brigade was of three rifle regiments, a sapper company and an artillery battalion. In the field the KomBrig would usually have some artillery, but not always.
A rifle regiment was three rifle battalions, an MG company, a mounted scout team, a mortar team, a signals team, and a commander's detachment.
In practice a division had between 60 and 240 MGs, so a battalion's share would be between 2 and 6, which meant the regiment's "MG company" would more likely be a platoon.
You almost never see mortars used in the civil war. I imagine any sappers would be grouped at the divisional level.
A regiment had three rifle battalions, each of three companies, and an MG platoon. The companies were officially of three platoons.
Red infantry usually fought alone, often with brigades operating independently. Due to the low troop densities, a brigade would normally cover a couple of kilometres of front. The only exception was the rare assaults on prepared positions, such as Perekop in 1920, Kakhovka or Tsaritsyn.
From mid-1919 onwards brigades would only rarely be composed of more than one origin. They would all be workers, internationalists, sailors, kursanty, ChON, VOKhR etc or, in the overwhelming majority of cases, all standard rifles.
Given the size of a division, a rifle battalion could be fewer than 200 men, and would rarely be over 500 men. It might or might not have its own MGs. So, depending on the size of the division, either the company or battalion of 150-200 men would be the normal manouevre element.
Attached support for a brigade would reasonably include one or two batteries of 4 light guns and some of the divisional cavalry. Less often there might be another light battery, an armoured car or heavy artillery.
Obviously the tactics employed depended on the relative skill of the commanders and men and the terrain. Comments are therefore meant to be general only. They assume that the battalion is big enough to operate the companies as the basic unit.
A battalion on the attack in the open would deploy outside effective range with two companies side by side, each in two lines in open order (so-called "chains"). The third company would be held in reserve.
Once in effective rifle range (perhaps 750 m) the advancing lines would start to open fire. If return fire was heavy, and the men were sufficiently trained, they would move forward in bounds – that is, one line would dash forward a short distance under covering fire from the other, whereupon the second would dash forward under cover of the first line.
MGs would as often as not be commanded at battalion level. They would support the attack or guard the flanks.
A regiment on the attack would advance with foot scouts in front, and two battalions wide, with the other in reserve to consolidate gains or to face attacks from unexpected directions.
The artillery would be generally at regiment level, to support the attack.
On the defence, trenches would be dug if the time allowed. Because of the low troop density and the ever-present risk to flanks, they would not be long strips necessarily. The fast-moving pace of the war and the ability of attackers to perform turning manouevres meant that trenches were generally pretty rough, even if troops were in place for a while. MGs and artillery would be well sited, given the amount of WWI veterans.
Again a third of the troops would be held in reserve, at battalion or regiment level.
Interesting detail: Red soldiers rarely marched long distances. In order to keep their mobility over long periods, and carry all the equipment that they required (because they could not rely on a solid supply system) they usually traveled in peasant carts. Therefore a regiment on the move could stretch many kilometres.
Five minutes of looking at photos of Red Army troops at the front shows that the typical Red unit was anything but uniform. The situation did not improve greatly as the war went on.
Apart from a few badges, all rifle units were largely identical.
Organisation is from the Encyclopedia of the RCW.
Unit sizes and the amount of support weapons are based largely on those orders of battle I have been able to assemble.