Was talking to a good friend about how pivotal Duvall's casting & performance in G1 was for his career. He was, given his exposure on TV anyway and small films, as mentioned, on people's radar. But it was Coppola's genius to give him a chance to occupy a very different character space, as the - as my very perceptive friend termed it - 'still waters run deep', utterly trustworthy & polished & contained consigliere of his adopted family in a major motion picture, which he carried magnificently.
If you, like me, hold GI & II near the top of the film pantheon you should see this :
Disclaimer: The video above is hosted on Youtube, and has not be reviewed by the staff of the Post-Dispatch.
There is also this, which I haven't yet seen but plan to, which is a dramatization of its making :