Senator Edward M. Kennedy, a towering figure in American public life for the last half-century, spent the waning moments of his life in the quiet embrace of his family, in a place he loved: his seaside home in Hyannis Port. Ever since that diagnosis, in May of 2008, it was clear to friends, political associates, and Americans across the country that, as the legendary scion of a political dynasty confronted his mortality, Kennedy was on dual missions: to battle cancer discreetly and with characteristic Kennedy grit and to cement his legacy, by helping to elect Barack Obama and pushing for health care reform.