Robert F. Kennedy announced his candidacy for president in the grand Senate Caucus Room on March 16, 1968, declaring that the United States, mired in war and riven by racism, ought to “stand for hope instead of despair.”

Eighty-one days later, he celebrated victory in California’s Democratic primary with an ebullient speech at the Ambassador Hotel in Los Angeles and walked off the stage into a pantry, where he was assassinated in front of news cameras and screaming supporters.

In a year that seemed determined to shake Americans’ confidence in the foundations of their society, Kennedy’s death at 1:44 a.m. Pacific time on June 6, 25 hours after he was shot, was one of the biggest inflection points. Sirhan Sirhan’s bullets not only demolished the hope for a savior candidate who would unite a party so fractured that its incumbent, President Lyndon B. Johnson, had decided not to seek re-election. Coming just two months after the assassination of the Rev. Dr. Martin Luther King Jr., they also fueled a general sense — not entirely unfamiliar today — that the nation had gone mad; that the normal rules and constants of politics could no longer be counted on.