Here’s a footnote from page 610 of “The Death of a President” by William Manchester that I think demonstrates a fundamental difference between JFK and LBJ. LBJ said that he wanted to continue the work of JFK. But, sadly, I cannot imagine that, at least once the war in Vietnam grew, LBJ had time to continue this JFK practice:
Kennedy personally wrote the family of every American who died in uniform during his Presidency. The lines to Box 813, Kirbyville, Texas, are particularly eloquent, but there were between forty and fifty such letters each month. Whenever one of them produced a reply, he invited the widow and children to Washington for a talk in the Rose Garden.