Deep operation (Russian: Глубокая операция, glubokaya operatsiya), also known as Soviet deep battle, was a military theory developed by the Soviet Union for its armed forces during the 1920s and 1930s. It was a tenet that emphasized destroying, suppressing or disorganizing enemy forces not only at the line of contact but also throughout the depth of the battlefield.

The term comes from Vladimir Triandafillov, an influential military writer, who worked with others to create a military strategy with specialized operational art and tactics. The concept of deep operations was a state strategy, tailored to the economic, cultural and geopolitical position of the Soviet Union. In the aftermath of the failures in the Russo-Japanese War, the First World War, and the Polish–Soviet War the Soviet High Command (Stavka) focused on developing new methods for the conduct of war. This new approach considered military strategy and tactics and introduced a new intermediate level of military art: operations. The Soviet Union's military was the first to officially distinguish the third level of military thinking which occupied the position between strategy and tactics.

The Soviets developed the concept of deep battle and by 1936 it had become part of the Red Army field regulations. Deep operations had two phases: the tactical deep battle, followed by the exploitation of tactical success, known as the conduct of deep battle operations. Deep battle envisaged the breaking of the enemy's forward defenses, or tactical zones, through combined arms assaults, which would be followed up by fresh uncommitted mobile operational reserves sent to exploit the strategic depth of an enemy front. The goal of a deep operation was to inflict a decisive strategic defeat on the enemy's logistical structure and render the defence of their front more difficult, impossible, or irrelevant. Unlike most other doctrines, deep battle stressed combined arms cooperation at all levels: strategic, operational, and tactical.

The Russian Empire had kept pace with its enemies and allies and performed well in its wars up to the 19th century. Despite some notable victories in the Napoleonic Wars (1803–1815) and in various Russo-Turkish Wars, defeats in the Crimean War (1853–1856), Russo-Japanese War (1904–1905), the First World War (1914–1918) and the Polish–Soviet War (1918–1921) highlighted the weaknesses in Russian and Soviet military training, organization and methods.^{[need quotation to verify]}

After the Russian Revolution of 1917, the new Bolshevik regime sought to establish a new military system that reflected the Bolshevik revolutionary spirit. The new Red Army (founded in 1918) combined the old and new methods. It still relied on the country's enormous manpower reserves and the Soviet program to develop heavy industry, which began in 1929, also raised the technical standards of Soviet arms industries to the level of other European nations. Once that had been achieved,^[when?] the Soviets turned their attention to solving the problem of military operational mobility.^{[need quotation to verify]}

Advocates of the development included Alexander Svechin (1878–1938), Mikhail Frunze (1885–1925) and Mikhail Tukhachevsky (1893–1937). They promoted the development of military scientific societies and identified groups of talented officers. Many of these officers entered the Soviet Military Academy during Tukhachevsky's tenure as its commandant in 1921–1922. Others came later, particularly Nikolai Varfolomeev (1890–1939) and Vladimir Triandafillov (1894–1931), who made significant contributions to the use of technology in deep offensive operations.

In the aftermath of the wars with Japan as well as experiences gained during the Russian Civil War several senior Soviet commanders called for a unified military doctrine. The most prominent was Frunze. The call prompted opposition by Leon Trotsky. Frunze's position eventually found favour with the officer elements that had experienced the poor command and control of Soviet forces in the conflict with Poland during the Polish–Soviet War. That turn of events prompted Trotsky's replacement by Frunze in January 1925.

The nature of this new doctrine was to be political. The Soviets were to fuse the military with the Bolshevik ideal, which would define the nature of war for the Soviet Union. The Soviets believed their most likely enemy would be the capitalist states of the west they had defended themselves against before and that such a conflict was unavoidable. The nature of the war raised four questions,