The eldest child of Joseph and Rose Kennedy, Joseph Jr. was set to enter his final year at Harvard Law School in 1943, but instead volunteered to serve as flier for the United States Navy in World War II.

He was sent to England, and died during a secret mission when an experimental aircraft loaded with explosives blew up over the English Channel.

The family was together in Hyannis Port on a Sunday afternoon in August when two priests came with news of his death, at age 29.

“My father took the two men upstairs,” Eunice Kennedy Shriver, Joseph Jr.’s sister, said later. “A little while later he came down and said, ‘We’ve lost Joe.’”

“Then he went back upstairs to his room and locked the door.”

When Joe Jr. was born, his grandfather, Mayor John F. Fitzgerald of Boston, announced to the news media that the newborn would become president someday.