I recently finished Joseph McBride's excellent (and massive) biography Searching For John Ford. It tells you everything you want to know about the man . . .
except who the hell he was.  The mysteries and contradictions of his
character simply cannot be sorted out.  I'm sure the same would be true
of Shakespeare if we had massive documentation and testimony about his
life.  The depth of the work in each man's case comes out of the
mysteries and contradictions and transcends them but sheds no light backwards on the
man himself.  Perhaps, to be a truly great dramatist, you have to
abandon all hope of a coherent self in real life.

The biggest revelation in the book, to me, was the extent of Ford's
WWII service, which was far greater than I realized — but even in that
arena, nothing he did seemed to satisfy him.  He told outrageous
lies about his wartime service, even when the things he actually did
were far more impressive.  Reading the book makes one more and
more convinced that Ethan Edwards comes as close to a portrait of Ford
the man as we will ever have — a psychotic searcher who does heroic
things that no one else can do, and then wanders off alone, permanently
lost.