Mary Jo Kopechne was 28 years old when she attended a party on Chappaquiddick Island, a tiny spit near Martha's Vineyard, on July 18, 1969. Joined by five of her friends from the 1968 presidential campaign for Sen. Robert F. Kennedy, Kopechne had already made waves in Democratic circles in Washington, working for a Florida senator before moving to Kennedy's Senate staff. She proved herself adept by helping to write an anti-Vietnam War speech for RFK, and helped write the address announcing his ill-fated candidacy for president.
Edward “Ted” Kennedy, meanwhile, was the last surviving son of Joseph Kennedy at the time of the party. After the wartime death of Joseph Jr. and the assassinations of John and Robert, Ted remained as the political leader of the family, a sitting U.S. senator from Massachusetts, with a potential run at the presidency in his future.