The LSM(R) was the U.S. Navy’s introduction of a new class of rocket support ship in late WW2. Modified from existing landing ships, it was an interim design to provide heavier inshore bombardment to support amphibious landings.

The evolution of rocketry design was also interesting with innovations from engineers at Caltech. (California Institute of Technology)

More on this topic:

Very detailed book on the subject:
"The US Navy's 'Interim' LSM(R)s in World War II: Rocket Ships of the Pacific Amphibious Forces" by Ron MacKay, Jr.

https://en.wikipedia.org/wiki/Landing...)