Multiple rocket launcher
A multiple rocket launcher (MRL) or multiple launch rocket system (MLRS) is a type of rocket artillery system.
Rockets have different capabilities than artillery, like longer range, and different payloads, for example considerably larger warheads, or multiple warheads.
Unguided rocket artillery is notoriously inaccurate and slow to reload, compared to artillery. To overcome this, rockets are combined in systems that can launch multiple rockets simultaneously.
Modern rockets can use GPS or inertial guidance, to combine the advantages of rockets with high accuracy.
History
The first multiple rocket launchers were made in Song-dynasty China. It was a primitive design where multiple fire arrows were fired from a gunpowder box. These also appeared later, in an expanded version, in the Joseon Dynasty of Korea.
World War Two
The first self-propelled multiple rocket launchers — and arguably the most famous — were the Soviet BM-13 Katyushas, first used during World War II and exported to Soviet allies afterwards. They were simple systems in which a rack of launch rails was mounted on the back of a truck. This set the template for modern multiple rocket launchers. The Americans mounted tubular launchers atop M4 Sherman tanks to create the T34 Calliope rocket launching tank, only used in small numbers, as their closest equivalent to the Katyusha. The Germans began using a towed six-tube multiple rocket launcher during World War Two, the Nebelwerfer, also called the "screaming mimi" by the allies.