Welcome, Freddie!

It's said that Bruno was called the "gentle Don" because he ran his Phila. family in a low-key, non-histrionic way. Probably the biggest contributing factor to the nickname was how he got the Donship after Joe Ida retired in '59. His rival was Antonio Pollina, who got the nod. Pollina thought Bruno would be a rival, and ordered him whacked. But Bruno was an old pal of Carlo Gambino. He appealed to his old pal, and thanks to Gambino's influence, Bruno became the Don. But, instead of whacking Pollina, he kept him on in a subordinate role, believing it'd be good for the family.
Of course, Bruno couldn't have gotten into the Mafia, and have gotten high up, without personal violence along the way.