Longest-serving defense secretary under Presidents Kennedy and Johnson dies at 93 Former Defense Secretary Robert McNamara has died. McNamara, 93, died at home in his sleep Monday morning, his wife Diana told The Associated Press. She said he had been in failing health for some time. Known as a policymaker with a fixation for statistical analysis, McNamara was president of the Ford Motor Co. when President John F. Kennedy asked him to head the Pentagon in 1961. McNamara worked for seven years as the defense secretary in the Kennedy and Johnson administrations, longer than any other person in that post. He headed the war department during the build-up of forces in Vietnam. He is considered the architect of the concept of "mutual assured destruction," a key feature of the nuclear arms race during the Cold War.