One flaw in the GF is that Michael, given his Marine service, would somehow be nervous or afraid when confronting gangsters (i.e., when he is standing outside the hospital when Vito is being set up for assassination, lights the cigarette, and his hands don't shake; and when he kills the Turk and McCluskey in the restaurant).

True, when Mike proposes to kill Solazzo and McCluskey, Sonny says to him: "It's not like the army, where you shoot them a mile away."

But anyone who knows anything about combat in the South Pacific during WW2, with the Marines fighting the fanatical Japanese, knows it was not "a mile away." Rather, the fighting was close-in, often hand-to-hand, and very, very brutal.

Just watch "Flags of Our Fathers"!

Michael, in fact (according to his testimony before the Senate Committee in GF2), won the Navy Cross, one of the highest decorations for heroism possible, just below the Congressional Medal of Honor. For Michael to have won the Navy Cross, he must have performed valiantly in some hellish combat. Not to mention that he was a Marine captain: That alone means he was plenty tough long before he "made his bones." He was trained to kill men with his bare hands!

So taking on a bunch of Mafioso would have been a piece of cake compared to what he did in the Marines.