I agree with this. The Katyusha is apparently one of the first Self-Propelled artillery used by the USSR, though it delivers rockets making it rocket artillery. Its shoot-and scoot approach, being fast enough to escape counter-battery fire, certainly seems accurate. As to effectiveness, it was quite feared. While inaccurate, 4 such trucks could supposedly release the same explosive power as 72 conventional artillery pieces. One interesting thing is it could take an hour to reload. Now what else …