Nebelwerfer means “Smoke Projector.”
This six-barreled rocket launcher was standard equipment in the German Army during the Second World War. It was called the “Moaning Minnie” by American troops due to the sound its cluster of rockets made in flight. It was fired electrically by remote control at a rate of six rounds every 90 seconds. It was one of the most effective and sophisticated pieces of rocket artillery used in the war.
Wikipedia translates it as “fog launcher”: https://en.wikipedia.org/wiki/Nebelwerfer
“Fog thrower” would’ve been my naive translation attempt, akin to “flame thrower” = “Flammenwerfer”.
I guess, there’s also “rocket launcher” = “Raketenwerfer”, which is much closer to what this weapon actually is.
Fog thrower is the most literal translation. That would imply its primary purpose was shooting smoke grenades.
Please send all of your translation notes to Rock Island Arsenal.