Soviet tactics, command and control and doctrine changed a lot during the war.

The Soviets entered ww2 with an interesting mix of experience from ww1, the Russian Civil War, their own type of deep battle doctrine and a political reversal of much of this, which proved disastrous.

The Eastern Front was never as locked or entrenched as the Western Front had been in ww1. The massed attack was on several occassions more successful here - the Central Powers broke through at Gorlice-Tarnow 1915, the Russians almost broke the Austro-Hungarians at the Brusilov offensive 1916 and the Germans managed to break Russia with their Baltic offensive 1917.

The Russian Civil War had also seen armies operating mostly independently from each other with a for the time minimal logistics train.

Generally, the Soviets had experienced that the more strong-willed and politically coherent army would win but also that adding resources to a successful attack would produce excellent results.

Tactically, the Soviets focused on overwhelming firepower and force on the attack and tenacity, excellent entrenchment and camouflage on the defence. The Soviets had also developed their own version of the German schwerpunkt idea in their deep battle doctrine, in which armoured, mechanised and cavalry formations would be grouped together, force a breakthrough and then act independently by rushing through and going for the deep of the enemy territory.

However, the 1937 and 1938 purges changed this. The idea of deep battle was lost, and armour was assigned to the infantry for support, although some dedicated mechanised and armoured formations reamined, as well as a large independent cavalry force. The purges also froze the initiative of the Red Army - NCOs and officers would not dare to do anything without orders for the risk of being accused of being a traitor. Tactical flexibility suffered heavily as a result.

In Spain, the Soviets more or less re-built the Spanish army 1937 along Soviet lines and tried to use zeal and discipline as replacements of tactical flexibility - while the Republicans had plenty of zeal, most soldiers came from the various militias and were unused to military discipline. The attempt to replace firepower and tactical flexibility with zeal and discipline spelled disaster during the Ebro offensive.

The Soviet system also proved devastatingly lousy during the Finnish Winter War. The lack of tactical flexibility, the lack of a short-range and long-range patrol doctrine in dense terrain (things the Finns excelled at) as well as operational and strategical planning failure in sending mechanised or motorised heavy formations into dense forests where they were road-bound and easy to cut up in mottis proved the failure of the Soviet system.

However, the Soviets did learn a lot from Finland, lessons they would put to good use against the Germans on the Eastern Front once they had recovered from the initial shock.

1941 the Red Army could in some circumstances be described as an armed mob without any real communications, leadership or even purpose. The shared leadership of formations between the commander and the political commissar, who was responsible for the loyalty and political zeal of the formation, also created problems - officers and commissars could argue back and forth on actions and officers might abstain from action that might be viewed as cowardice (a tactical retreat, for example) or going outside orders.

The 1945 Red Army was a completely different beast and one of the best armies in the world. What happened?

The losses in Finland, and especially in the first year of the Eastern Front shock the Soviets to the core and allowed them to start learning what they were good at - but especially what they were not good at.

The Soviets understood that they could not match the Germans in tactical flexibility and in the training and education of NCOs and lower officers (since they did not have the same stock of educated people to draw from and the extreme casualties they suffered required them to train new soldiers and their NCOs and lower officers quickly). So the Soviets developed that they called an operational doctrine. Specialised staffs of officers from the central command, STAVKA, was attached to sectors of the front where heavy fighting was expected. Heavy artillery, which had been attached to divisions and made them heavy and unwieldy (and hard to use since the divisions lacked the radio equipment and dedicated artillery staff as well as forward observers etc to use it well), was moved to special artillery formations under STAVKA control. Large armoured and mechanised formations were created and placed under STAVKA control as well.

These formations were attached to these staffs and used where it was deemed necessary. If an attack ran into heavy resistance and slowed down, resources was quickly shifted to a part of a front where the attack was more successful. Reinforcements, supplies and replacements were monitored closely by the dedicated staffs from STAVKA and used where they would be most effective.

The Soviets never had the same level of tactical independence as the Germans did with their auftragstaktik and knew they could not match the Germans in tactical skill, so they developed the operational doctrine to counter the Germans.

Adding to this was maskirovka or large scale camouflage and deception. Hiding troops by radio silence, camouflaging large formations and especially creating the false impressions they were at another part of the front by laying phone lines, creating massive radio chatter, placing dummy tanks and artillery and have trucks run back and forth to create the impression of new roads and well-used supply lines, the Soviets concentrated overwhelming force and tricked the Germans into assigning their reserves elsewhere and then used operational flexibility to keep their enemies off their balance.

These two examples - operational doctrine and maskirovka is the reason for the still pervasive myth of the overwhelming avalance or human wave attack from the Soviets. For the first 20-30 years after ww2, western authors writing on the Eastern Front only had access to German officers and accounts, not Soviets. The Germans saw only a lack of tactical flexibility and the overwhelming superiority in firepower and numbers the Soviets deployed on the attack, and their conclusion was that they were drowned in men and materiel rather than being outfought. They never saw the refined planning and execution that went into maskirovka nor the detailed work and meticolous attention to detail that went into staff work for the operational battle.

The Soviets, learning from the Finns, also created the idea of constant small raids, patrols and infiltration for information gathering at a large scale - the Western Allies and the Germans had used patrol acticity to take prisoners and do recoinnasance on the Western Front in ww1, but the Finns taught the Soviets about long-range patrol activity, something which they used frequently and with good effect against the Germans.

The western allies developed their own version of maskirovka (notably by creating their false army that was to attack Calais on D-day), but the Soviets pioneered it, andit became standard tactics for all armies, although at a larger scale and more common among the Soviets and their Warsaw Pact allies during the Cold War.

Long-range patrol activity is now also a very common concept in all armies - special forces usually take this duty nowadays, akin to how the British commandoes operated druring ww2.