[1] He simultaneously served as a member of the President's Advisory Panel on Ethics and Conflicts of Interest in Government beginning in 1960.
[1] In 1971, Cyrus R. Vance and David Rockefeller soon appointed Manning as the first president of the Council of Foreign Relations (CFR).
[1][3] Following the end of his tenure at CFR, Manning joined Paul, Weiss, Rifkind, Wharton & Garrison, a law firm based in New York City.
[1] In 2001, Manning was awarded the Certificate of Meritorious Achievement from the United States Office of Government Ethics for the Executive Branch.
[2] He was survived by his wife, Alexandra Zekovic, five children, and six grandchildren.