Hmmm...Katyuska...Stalin's pipe organ...
At the risk of starting YetAnotherReligiousWar(tm)[1] I've read the artillery rockets of WWII were more psycological as a saturation weapon than practical. Tube artillery was more accurate and could get more ordinance on target quicker.
Still...can you imagine something more fun for attacking a town?
[1] Ever read a thread about aircraft performance? Invariably someone calls someone else's mother an army boot wearing person of questionable moral fiber, even though it's the airplane's roll rate being debated.