The Katyusha (Russian: Катю́ша, IPA: [kɐˈtʲuʂə] ⓘ) is a type of rocket artillery first built and fielded by the Soviet Union in World War II.

Multiple rocket launchers such as these deliver explosives to a target area more intensively than conventional artillery, but with lower accuracy and requiring a longer time to reload.

This mobility gave the Katyusha, and other self-propelled artillery, another advantage: being able to deliver a large blow all at once, and then move before being located and attacked with counter-battery fire.

Today, the nickname Katyusha is also applied to newer truck-mounted post-Soviet – in addition to non-Soviet – multiple-rocket launchers, notably the common BM-21 Grad and its derivatives.

[3] Because they were marked with the letter K (for Voronezh Komintern Factory),[3][4] Red Army troops adopted a nickname from Mikhail Isakovsky's popular wartime song, "Katyusha", about a girl longing for her absent beloved, who has gone away on military service.

[6] German troops coined the nickname "Stalin's organ" (Stalinorgel), after Soviet leader Joseph Stalin, comparing the visual resemblance of the launch array to a pipe organ, and the sound of the weapon's rocket motors, a distinctive howling sound which terrified the German troops,[7] adding a psychological warfare aspect to their use.

[8] Katyusha rocket launchers, which were built in Voronezh, were mounted on many platforms during World War II, including on trucks, artillery tractors, tanks, and armoured trains, as well as on naval and riverine vessels as assault support weapons.

A battery of four BM-13 launchers could fire a salvo in 7–10 seconds that delivered 4.35 tons of high explosives over a 400,000-square-metre (4,300,000 sq ft) impact zone,[2] making its power roughly equivalent to that of 72 conventional artillery guns.

The weapon's disadvantage was the long time it took to reload a launcher, in contrast to conventional artillery guns which could sustain a continuous, albeit low, rate of fire.

In June 1938, GDL's successor Reactive Scientific Research Institute (RNII) began building several prototype launchers for the modified 132 mm M-132 rockets.

The Katyusha was inexpensive and could be manufactured in light industrial installations which did not have the heavy equipment to build conventional artillery gun barrels.

The cross-country performance of the Studebaker US6 2½-ton 6×6 truck was so good that it became the GAU's standard mounting in 1943, designated BM-13N (normalizovanniy, 'standardized'), and more than 1,800 of this model were manufactured by the end of World War II.

[21] The multiple rocket launchers were top secret at the beginning of World War II and a special unit of NKVD troops was raised to operate them.

[14] On August 8, 1941, Stalin ordered the formation of eight special Guards mortar regiments under the direct control of the Reserve of the Supreme High Command (RVGK).

[27] During the Cold War, the Soviet Union fielded several models of Katyusha-like MRL, notably the BM-21 Grad launchers somewhat inspired by the earlier weapon, and the larger BM-27 Uragan.

Advances in artillery munitions have been applied to some Katyusha-type multiple launch rocket systems, including bomblet submunitions, remotely deployed land mines, and chemical warheads.

The Viet Minh deployed them against the French Far East Expeditionary Corps during the Battle of Dien Bien Phu at the end of the First Indochina War.

By decree of the President of the Soviet Union Mikhail Gorbachev dated June 21, 1991, I. T. Kleymenov, G. E. Langemak, V. N. Luzhin, B. S. Petropavlovsky, B. M. Slonimer and N. I. Tikhomirov were posthumously awarded title of the Hero of Socialist Labour for their work on the creation of the Katyusha.