No, to say "walking is difficult" you would say "ambulare difficile est". Not "ambulans difficile est". You should see Pacifica's guide on gerunds vs present participles vs gerundives vs infinitives in the Grammar Tips sub-forum.
"Casibus" means "to/with, etc. the accidents/chances, etc.". It's from "casus, casūs, fall, overthrow; chance/fortune; accident, emergency, calamity, plight; fate;
grammatical case; termination/ending (of words);".
Perhaps not the form you were looking for.
Your phrase would translate as "into memory with peace to the calamities."