Multiple Launch Rocket Systems are pretty handy. Our current MLRS and HIMARS have evolved from area suppression weapons into long range precision weapons with the Guided MLR round, and the ATACM long range guided missile. But for most of their history, rockets have been relatively short ranged, area fire weapons. They offer a massive barrage, but at the expense of long reloading times, and relatively poor accuracy.
During World War II, the Army used large numbers of 4.5” barrage rockets. At the very tail end of the war, the spin stabilized rocket was introduced to improve on the poor accuracy of the earlier fin stabilized rockets. The M16 rocket was fired from the T-66 launcher.
Shortly after the end of the Korean War, the US pretty much got out of the barrage rocket business. But the Soviet Union, who’d had great success with theirs in World War II (and were always big fans of artillery), used the 122mm Grad rocket launcher, primarily as a counter-battery weapon, but also for suppressive fires. The BM-21 is much longer than contemporary US rockets, giving it much greater range. Simple, cheap, and easy to use, the BM-21 Grad is mostly gone from Russian service, but is still used by a lot of former client states.
Since the 122mm rocket is still so popular, some folks are even now making launchers for it. And this might be the ultimate evolution of that concept.