He also wasn't averse to a bit of brutality, though of course committed by someone other than himself.
During the wars that eventually put him on top, his rival sent word to Al Capone asking for some gunmen.

From the novel:

"Maranzano sent a call to Capone for his two best gunmen to
come to New York to eliminate the upstart. The Corleone
Family had friends and intelligence in Chicago who relayed the
news that the two gunmen were arriving by train. Vito Corleone
dispatched Luca Brasi to take care of them with instructions
that would liberate the strange man’s most savage instincts."

The novel goes into some detail about what happened next; brutality is a very apt word.