Hagen's removal as Consigliere was a move made by both Michael and Vito. On the surface, the premise of the move was that Tom was not a wartime consigliere, which was true. A deeper reason for this move was implied (in the novel) but never actually completely brought to the surface. Michael and Vito felt that Tom needed to have no part or role whatsoever in Michael's move to take out the Family heads. The implication is that Tom needed to be removed because Tom sat behind Vito (figuratively and literally) when he swore on the souls of his grandchildren that, as long as he was not provoked, he would not be the one to break the peace, and thus a party to "Vito's promise".

Though Vito made this peace that weakened him for a moment in time, his master plan was to: A) get Michael back in one piece B)secretly rebuild the family from within (who says you don't need to pay attention to your own family...) and ultimately get his revenge against the Dons that forced him into doing something against his will. Tom referred to the Don's plan as masterful riddle that he couldn't quite figure out, but ultimately was able to once he put on his Sicilian thinking cap.

My questions: 1. Did Don Vito break his promise and code of honor? Though Michael accepted full responsibility for the planning and carrying out of the hits, it was Vito that first conceptualized the move-long before Michael's return. Was Tom's removal and Michael's insistence that it was he that was responsible the technicality that Vito hung his hat on? Can we attribute Mary's death to Vito's actions?