On May 4, 1970 the Ohio National Guard opened fire on unarmed students protesting America´s invasion of Cambodia. Four students were killed and nine were wounded. The incident triggered national outrage in a country already divided over the Vietnam War. In the days that followed more than four million students rose up in dissent across 900 campuses, generating the only nationwide student protest in U.S. history. Fearing civil unrest, President Nixon was taken to Camp David for his protection.