activists in which group later joined the antiwar movement
Many in the peace movement within the U.S. were students, mothers, or anti-establishment hippies. Opposition grew with participation by the African-American civil rights, women's liberation, and Chicano movements, and sectors of organized labor. Additional involvement came from many other groups, including educators, clergy, academics, journalists, lawyers, physicians (such as Benjamin Spock), and military veterans. Their actions consisted mainly of peaceful, nonviolent events; few events were deliberately provocative and violent. In some cases, police used violent tactics against peaceful demonstrators. By 1967, according to Gallup Polls, an increasing majority of Americans considered U.S. military involvement in Vietnam to be a mistake, echoed decades later by the then head of American war planning, former U.S. Secretary of Defense Robert McNamara.