What is J.R. Oppenheimer's importance in US history?

Oppenheimer was not only chief scientist on
the atomic bomb project but was the first major atomic scientist post-war to take a
public stand against continued research into nuclear weapons, specifically the
development of the hydrogen bomb. The project was originally termed the
"Manhattan Engineering District," although the code name changed monthly during the
war.  It was a joint project between the US, UK and Canada, carried out in the US
because there was no secure location in Britain during the war.  The British weapons
project TUBE ALLOYS was the basis of the work.  After the war the scientists involved
split into groups, some opposing further weapons research, some for it.  Edward Teller
was a brilliant physicist who was also an opportunist, and seeing an unlimited future of
government sponsored research ahead he tirelessly worked to ruin Oppenheimer's
reputation.  In the Red Scare in the wake of the disastrous beginning of the Korean War,
Oppenheimer was easy prey for people like Teller and McCarthy.  In 1953 his security
clearances were revoked,effectively ending his work with governmental projects.  From
1947 through 1966 he was director of the Institute for Advanced Studies, at Princeton. 
Prior to the war he had been simultaneously assistant professor of physics at UC Berkely
and the California Institute of Technology.

Interestingly
enough, Robert Oppenheimer in the 1930s was the first physicist to suggest the existence
of what are today termed "black holes," as well as important work in the theory of
cosmic ray showers and what eventually became known as quantum tunneling.  He was one of
the greatest of American scientists, and a man who the country owed a great debt of
gratitude to but who was treated shabbily.