Did some reading myself, more precisly I finally reached those points in the novel, lol. Anyways...

The war is described as the war between the Corleone Family and The Five Families. Therefore, logically, the Corleone Family must be number six. Who's the unnamed fifth Family then? Well just flip back a chapter or two and you'll find this:

Quote
Originally written by Mario Puzo:
It was Brasi, operating alone when one of the six powerful families tried to interfere and become the protector of the independents, who assasinated the head of the family as a warning. Shortly after, the Don recovered from his wound and made peace with that particular family.
Does it say that family got eliminated? No. Does it say the Corleone Family is not counted among the six, no. Earlier even it says "[there] were five or six "Families" too powerful to eliminate." So, Corleone must be being counted among the six. So, we have Corleone, Cuneo, Barzini, Stracci, Tattaglia, and the unknown Family. Plus the Bocchicchio Family as the negotiators. There, perhaps this will solve the problem. Plus I can finally put that A in logic to use, hehe.


What do you think this is the Army, where you shoot'em a mile away?

You've gotta get up close like this and bada-bing! you blow their brains all over your nice Ivy League suit.