Soviet Deep battle, in short, was the Soviet Union's attempt to develop an Operational art - the 'middle ground' of battle that lays between the tactical and the strategic. "Operational" level of warfare was the natural evolution of what Chandler described as its embryonic predecessor, Napoleonic "Grand Tactics." It was Military science's attempt to keep up with the growing scope and scale of the industrialized battlefield. War is no longer a series of short and sharp engagements but rather a flowing affair, with larger, strategically oriented battles ('operations') that often encompass several smaller, shorter battles-within-battles (tactical engagements).
Deep Battle, or Deep Operations in particular first begins to develop as a theory in the 1920s. Like most developing theories of Mobile Operations at this time, it had one, over-arching goal: Get the battlescape moving, and keep it moving^1. The experiences of the Russian Civil War was the first source of practical experience with which they could create new theory out of - and it fails to reflect the full integration of Mechanization that the wars of the 1930s of and 1940s would have. This is the most immediate difference from Theory, in which the Soviets imagined echelons of Infantry and Cavalry, and Practice, in which tailor-made Corps would be created to form different echelons of the attack. Maneuver space was initially taken for granted, rather than thought of something that would have to be created through larger breaches in a deep, anchored line. ^2 Original Deep Battle theory still sought the 'knock-out blow' of earlier wars; but by the end of the initial period of theorizing several individuals, such as Tukhachevsky, were already reaching the conclusion that this would be an impossible goal in a modern, total war.^3
The purges that swept the RKKA in the 1930s took minds like Tukhachevsky away, or silenced them. This meant that the next natural step in the evolution of Deep Battle - a switch to a more mechanized focus and setting up a series of penetrations rather than one, war-ending one, was greatly retarded. The practice would have to be learned under fire, in the years 1941-43. There would be many false starts. Early application of the theory would underestimate the mass needed to effect penetrations. At the divisional level, Soviet Rifle groups would often be attacking on too broad a front, and it would require several attacks by multiple echelons to achieve penetration. This would be both time consuming and costly, and allow the Germans to move hitherto spread reserves into positions of concentration from which to seal off Soviet breakthroughs before they could become problematic. ^4
The problem of deployment was also a problem of experience, commander skill (at all levels) and simple organization. The Red Army, very much in an emergency state in the winter of 1941 was using formations developed in the late 1930s based around a strong, robust Officer Corps - which had been largely bled white in that same time period. Formations weren't just attacking on too broad a front, they were too large, too unwieldy for the very mixed bag of RKKA commanders to apply universally. The next great step towards creating a series of mini-battles of encirclement was to downsize the rosters of rifle divisions and get rid of the over-large Corps meant to exploit penetrations. From there, bitter loss and the stern lecturer of battle would refine the RKKA's skill in deploying these streamlined formations. Goals became more realistic; and the first true evidence of shifting to smaller, more manageable, but equally decisive penetrations and encirclement emerge in the year 1943.
The practice was 'established' so to speak during the Stalingrad counterattacks, in which the Russian General staff were able to convince Stalin to embark upon two smaller, more manageable penetrations. The idea of deception^5, often touted but rarely performed with much grace during the Winter of 1941/42, was also seen in a satisfactory form. Not only would the Soviets mass the proper amounts of forces to first penetrate, then widen the battle-scape (what the US Combined Arms School refers to as reaching 'operational depth' or 'operational complexity') they would be able to do so in secret. The German reserves, what little they had, were never able to concentrate in time to effectively seal off the numerous penetrations. The smaller, more-realistic scope of the operations around Stalingrad also allowed the Soviet's Mechanized corps to form proper blocking positions to prevent relief. Preventing a failure that was all too common to see in earlier counterattacks: Germans breaking into, or out of, pockets.^6
^1:
"Soviet military theorists pondered the nature of modern war and specific dilemmas of the First World War, the most important of which was how to restore mobility and maneuver to the....stagnant battlefield. Soviet military theorists were assisted in this task by the experiences of the Russian Civil War....a conflict which was, in many ways and for many reasons, different from the First World War. However, the Soviets were not unique either in the questions studied or the conclusions reached...."
Soviet Operational Art: In Pursuit of Deep Battle Glantz, David M. Page 19.
^2:
"Soviet employment of limited forces over vast areas of Russia and the relatively unsophisticated weaponry of the combatants gave the [Civil War] more of a maneuver character...the creation of shock groups permitted rapid penetration of shallow enemy tactical defenses....in these circumstances it is natural that in the postwar period Soviet theorists would turn their attention to applying the lessons of the Civil War...
Ibid., page 20.
^3:
"The impossibility on a modern wide front of destroying the enemy army by one blow forces the achievement of that aim by a series of successive operations."
Ibid., page 21.
^5: Deception is often considered a corner-stone of Soviet Deep Battle, to the point where it is more often referred to by its native name of Maskirovka, becoming essentially a term in and of itself. Many authors detail, with varying levels of confusion, practical steps meant to ensure Maskirovka. I find George Nipe Jr's criteria, found in his book Decision in the Ukraine, the easiest to read for its almost legalistic, point-by-point listing of its tenets. Soviet Deception often entailed some or all of these elements:
- Concealing the actual movement and preparations for the movement of troops and supplies into the concentration area. This included concealing facilities for storage of fuel and supplies, troop shelters, road and bridge construction, etc.
- Strictly limiting movement of these forces or supply units during the daytime.
- Camouflage of the assembly positions and dispositions of the attack force.
- Elimination of battle reconnaissance by units of the attacking force.
- Strict radio silence of all arriving units, especially mobile forces.
- No firing of artillery that was designated for the support of the attack for registration purposes. Registration was accomplished by having roving batteries or already sited guns provide this information.
- Deceptive measures regarding operations of radio and other communication means.
- Limiting knowledge of counteroffensive plans to as few people as possible.
- Limiting effectiveness of German air reconnaissance.
(Page 171 of the above mentioned piece)
^6; Further reading: Antony Beevor's Stalingrad details the Operations Little Saturn and Uranus in surprising depth and in an enjoyable manner. The basic reasons of why the initial 1943 operations succeeded where the 1941/42 operations often rebounded are laid out, at the very least: German raggedness, Soviet patience, Soviet deception and most importantly realistic appraisal of both force's capabilities - something so dearly lacking before.
In a nutshell, Soviet Deep Battle is a two-phase operation: breakthrough and exploitation. So far, quite the military banality... But then there is a question of scale...
Breakthrough in WWII Soviet deep operations is achieved through overwhelming concentration of artillery and shock troops, the likes of which had never been seen before. Nevertheless, it fails if the opponents manages to foresee it so the key is operational deception, for which operation Bagration is a perfect example... So the brutality of this opening must not make one forget how much effort has been expended in keeping its buildup secret. Tactically, the Soviet planner might actually try his luck at several spots but at the scale of Deep Battle this is a minor implementation detail.
Exploitation phase begins when gaps have been opened to penetrate to the enemy's rear. This is not tactical envelopment - whole tank armies are poured through the gap to reach operational objectives 200 kilometers in the enemy's rear. The level of coordination and logistics required to achieve that is staggering - the Soviet on-the-job learning process has been extremely costly: the first attempts were disasters and it took a few to reach the level where they could collapse whole German fronts by striking deep objectives. For an in-depth analysis of how they got there, I recommend David M. Glantz's "From the Don to the Dnepr: Soviet Offensive Operations, December 1942 - August 1943"
Behind enemy lines, armored units go after the enemy's coherency in a systemic way - seeking soft critical targets such as logistics nodes. In that phase, massive use of forward detachments ("peredovye otriady" in Sverdlov's words, cited by Glantz in "The Soviet Conduct of Tactical Maneuver") operating autonomously has ingredients of recon-pull even if it is in no way comparable to anything resembling Auftragstaktik.
The fine line between boldly seizing far objectives and getting stranded far from friendlies has often been crossed... In "From the Don to the Dniepr", Glantz mentions "Much testing was necessary to instill in commanders the flexibility necessary to carry out deep offensives. This required a balance between initiative and obedience that was hard to achieve. Some commanders inclined toward the latter (Rybalko at Khar'kov) while many evidenced a degree of initiative that bordered on recklessness (for example Katukov at Bogodukhov, Vatutin in the Donbas). It would involve several operations of the scale of Belgorod-Khar'kov for the Soviets to begin mastering this problem"
You might be interested in those previous threads: