But in this case, why would the war have started in the first place if Sonny said no for the deal and Mike wouldn't have killed McCluskey?
I think that the Corleones under Sonny would have fought to gain justice or vengeance over Vito's killing.
Michael: "If they had gotten the old man, what would you have done?"
Sonny: "Sollozzo is dead meat. I don't care what it costs. I don't care if we have to fight all the five families ..."
