Deep operation
The elimination of these allies or a successful advance to their borders would deny Germany military resources, or at least destabilise the Axis bloc in the Balkans.
The operational method revolved around outmanoeuvring their opponents. The nature of the bulge meant the Red Army could build strong fortifications in depth along the German axis of advance. Two rifle divisions defended the first belt, and one defended the second. A first belt division would only defend an area of 8–15 kilometres wide and 5–6 kilometres in depth. Successive defence belts would slow German forces down and force them to conduct slow and attritional battles to break through into the operational depths. Slowing the operational tempo of the enemy would also allow the Soviet intelligence analysts to keep track of German formations and their direction of advance, enabling Soviet reserve formations to be accurately positioned to prevent German spearheads breaking through each of the three main defence belts. Intelligence would also help when initiating their own offensives (Operation Kutuzov and Operation Polkovodets Rumyantsev) once the Germans had been bogged down in Soviet defences. The overwhelming contingent of Soviet armour and mechanised divisions was given to the operational reserves for this purpose.
The tactical level relied heavily on fortified and static defences composed of infantry and artillery. Anti-tank guns were mounted throughout the entire depth of the defences. Few tanks were committed to the tactical zones and the nature of the defences would have robbed them of mobility. Instead, only a small number of tanks and self-propelled artillery were used to give the defences some mobility. They were distributed in small groups to enable localised counterattacks. Such tactics slowed the Germans, forcing them to expend strength and munitions on combating the Soviet forward zones. The Soviets had counted on the Germans being stopped within the tactical zones. To ensure that this occurred, they distributed large numbers of anti-AFV (armoured fighting vehicle) and anti-personnel mines to the defences.

Outcome: The Germans began their offensive, as predicted, on 5 July 1943, under the codename Operation Citadel. The Soviets succeeded in limiting them to a slow advance. In the north, the German 9th Army advanced south from Orel. The Germans failed to breach the main defence lines, stalling at the third belt. The German armies had been forced to commit their mobile reserves to the breakthrough. This allowed the Soviets to conduct the operational and offensive phase of their plan; Operation Kutuzov. Striking the 2nd Panzer Army, the Soviet's fresh operational forces, heavily mechanized, threatened to cut off the German 9th Army. Had they succeeded, nothing would have stood between the Red Army and the strategic depth of German Army Group Centre's front. However the Germans were able to stem the advance by committing their mobile reserves and organize a withdrawal. Still, the two German armies had been worn down, and the Soviet forces in the north had won the strategic initiative.
In the south, the Soviet plan did not work as effectively and the contingency plan had to be put into effect. The German formations succeeded in penetrating all three Soviet defence belts. This denied the Soviets the opportunity to pin them down in the tactical defence belts and release their operational reserves to engage the enemy on favourable terms. Instead, operational forces for Operation Polkovodets Rumyantsev that were intended for the southern counteroffensive, were ordered to at and near Prokhorovka. This led to the Battle of Prokhorovka. While the tactical deployment and operational plan had not worked as flawlessly as it had in the north, the strategic initiative had still been won.

Other campaigns: With improved material means and tactical aptitude enabling complicated large-unit maneuvers, the following later campaigns were able to exhibit an improved application of the Deep operation doctrine: 

Dnieper–Carpathian Offensive
Operation Bagration
Second Jassy-Kishinev Offensive
Vistula–Oder Offensive

Cold War: 

Central Europe: The Soviet Union and its Warsaw Pact allies used their massive superiority in numbers and the idea of Deep Battle to intimidate NATO over the Inner German border. Some Western observers predicted that the Warsaw Pact could use a mixture of speed and surprise to overrun Western Europe in around 48 hours. While massive air strikes using enormous numbers of aircraft would devastate NATO infrastructure and reinforcements, VDV (airborne units), Spetsnaz ("special purpose troops", i.e. special forces) and naval infantry would clear the way for the torrent of tank and motor-rifle divisions that would soon cross the border. The forward units of these tank and motor rifle divisions would be given the task, rather unusually, of avoiding engagements with the enemy and simply to advancing as far and as fast as possible, therefore enabling a victory before any replacement aircraft and REFORGER units came to Europe from North America.

Asia: Ever since the 1960s when the Sino-Soviet alliance came to an abrupt end, the Soviet High Command considered invading China by deep battle offensive operations, envisaging a rapid drive deep towards the latter's main industrial centers before they could have a chance to mount a credible defense or even stage a counterattack. However, the extremely vast numbers of the Chinese People's Liberation Army and their knowledge of the terrain, coupled with their then-recent possession of nuclear weapons, made such a drive the Soviets were to execute extremely unlikely. Although both sides nearly went to war in three separate occasions in 1968, 1969 and 1979 respectively, the Soviets were rather hesitant to go to war and invade China, thanks to the fact that both possessed huge armed forces and nuclear weapons at their disposal.

21st century: In the spring of 1999 came the crisis in Kosovo and NATO’s Operation Allied Force as a result of R2P doctrine. The combat operations featured no land warfare, and therefore no front line can be said to have existed. The air war over Serbia was a "deep battle" as Air Force bombed strategic targets and fielded forces. Army Major General Robert H. Scales came to the conclusion that the US needed "strategic pre-emption", defined as the "use of airpower to delay the enemy long enough for early arriving ground forces to position themselves between the enemy and his initial operational objectives."

Major proponents: Mikhail Tukhachevsky
Vladimir Triandafillov
Georgii Isserson
Nikolai Efimovich Varfolomeev
Georgy Zhukov

See also: Operational art
Tank Corps (Soviet)
Mechanized Corps (Soviet)
Blitzkrieg

References: 

Citations: 

Bibliography: Glantz, David M., Col (rtd.) Soviet Military Operational Art: In Pursuit of Deep Battle, Frank Cass, London, 1991a. ISBN 0-7146-4077-8.
Glantz, David M. (1991b). The Soviet Conduct of Tactical Maneuver: Spearhead of the Offensive (1. publ. ed.). London u.a.: Cass. ISBN 0-7146-3373-9.
Grant, Rebecca (1 June 2001). "Deep Strife". Air & Space Forces Magazine.
Habeck, Mary. Storm of Steel: The Development of Armor Doctrine in Germany and the Soviet Union, 1919–1939. Cornell University Press, 2003. ISBN 0-8014-4074-2
Harrison, Richard W. The Russian Way of War: Operational Art 1904–1940. Lawrence, Kan.: University Press of Kansas, 2001. ISBN 0-7006-1074-X
Krause, Michael and Phillips, Cody. Historical Perspectives of Operational Art. Center of Military History, United States Army. 2006. ISBN 978-0-16-072564-7
Naveh, Shimon (1997). In Pursuit of Military Excellence; The Evolution of Operational Theory. London: Francass. ISBN 0-7146-4727-6.
Simpkin, Richard. Deep Battle: The Brainchild of Marshal Tukhachevsky. London; Washington: Brassey's Defence, 1987. ISBN 0-08-031193-8.
Watt, Robert. Feeling the Full Force of a Four Point Offensive: Re-Interpreting The Red Army's 1944 Belorussian and L'vov-Przemyśl Operations. The Journal of Slavic Military Studies. Routledge Taylor & Francis Group. ISSN 1351-8046

External links: Blythe, Wilson C. Jr. “The Conduct of War: Reemergence of Russian Military Strength Warrants Study of Soviet Operational Theory in the Interwar Era”, in The Officer (Winter 2015), accessible online at: https://www.academia.edu/31966162/The_Conduct_of_War_Re_emergence_of_Russian_Military_Strength_Warrants_Study_of_Soviet_Operational_Theory_in_the_Interwar_Era
The Evolution of Operational Art by Georgii Isseson, 1936 – PDF, available on United States Army Combined Arms Center's website
"Georgii Isserson: Architect of Soviet Victory in World War II": Video on YouTube, a lecture by Dr. Richard Harrison, via the official channel of the U.S. Army Heritage and Education Center