SLC tried to get his nephew Sammy Moffett into West Point around 1875, and
he
began some correspondence  with people there then; he also wrote to the
Secreta
ry of War on his nephew's behalf.  This is in addition to the frequent
visits
he made there to read.  I suspect, but I don't know for certain, that his
work
with Grant on the memoirs also got him into that circle.
     Andy Hoffman