My favorite movie ever. Seen it about 100 times, but here’s a question I’ve never been able to answer:
How did Don Corleone “know it Barzini all along” (that killed Sonny) after the big meeting where him and Tattaliga hugged it out and the truce allowing drugs to be sold was made?
My assumption watching the movie was just that Don Vito simply had the instinct to know which was beyond what a normal person would figure out.
Because Barzini was using Tattaligia to try to run the Corleone’s out of New York. This became obvious during the meeting of the 5 heads when Barzini took over for Tattaligia in telling Don Vito what the terms of the agreement would be. In acquiescing to Barzini in the meeting, Tattaligia showed that he was just the foil being used to attempt to force the Corleone’s out.
It was very subtle and was something that I did not pick up on the first few times that I watched the movie.
Watch Tattaglia during the meeting - he gives glances to Barzini indicating that there is some coordination there, and it's pretty clear that Barzini wants them involved in the drug trade.
Vito also had little respect for Tattaglia ("Tattaglia's a pimp. He could have never outfought Santino.") and knew someone else had to be backing him.