The monument to Katyusha multiple rocket launcher near Poltava

Katyusha multiple rocket launchers are a type of rocket artillery first built and fielded by the Soviet Union in World War II (see pictures above). Compared to other artillery, these multiple rocket launchers deliver a devastating amount of explosives to an area target quickly, but with lower accuracy and requiring a longer time to reload. They are fragile compared to artillery guns, but inexpensive and easy to produce. Katyushas of World War II, the first self-propelled artillery mass-produced by the Soviet Union, were usually mounted on trucks. This mobility gave Katyushas another advantage: being able to deliver a large blow all at once, and then move before being located and attacked with counter-battery fire.
The multiple rocket launchers were top secret in the beginning of World War II. A special unit of the NKVD secret police was raised to operate them. On July 7, 1941, an experimental artillery battery of seven launchers was first used in battle at Orsha in Belarus, under the command of Captain Ivan Flyorov, destroying a station with several supply trains, and causing massive German Army casualties. Following the success, the Red Army organized new Guards Mortar batteries for the support of infantry divisions. A battery's complement was standardized at four launchers. They remained under NKVD control until German Nebelwerfer rocket launchers became common later in the war.
On September 25, 1941 they were first used on the territory of the present day Ukraine. There is a monument dedicated to Katusha in the village of Dykanka (35 km. north from Poltava) shown on the picture below. The success and economy of multiple rocket launchers (MRL) have led them to continue to be developed. During the Cold War, the Soviet Union fielded several models of Katyushas, notably the BM-21 launchers fitting the stereotypical Katyusha mould, and the larger BM-27. 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.
See video at
http://www.youtube.com/watch?v=iRhv9_jHDhk
Read more about Katusha at
http://en.wikipedia.org/wiki/Katyusha_rocket_launcher