The AP has an article on McNamara which tells why he is so despised. The vast majority of casualties came after he believed we should change course but he lied to the world about what was happening. There is blood on his hands.
" McNamara disclosed that by 1967 he had deep misgivings about Vietnam - by then he had lost faith in America's capacity to prevail over guerrillas who had driven the French from the same jungle countryside.
Despite those doubts, he had continued to express public confidence that the application of enough American firepower would cause the Communists to make peace. In that period, the number of U.S. casualties - dead, missing and wounded - went from 7,466 to over 100,000."
