By the mid-1930s, from London to America, the Churchills and the Kennedys shared an ever-widening circle of friends, lovers and political associates --- soon shattered by World War II, spying, sexual infidelity, and the tragic deaths of JFK's sister Kathleen and his older brother Joe Jr. By the 1960s and JFK's presidency, these two powerful families had overcome their bitter differences and helped to define the “greatness” in each other.