In 1537, Florentine Duke Alessandro dei Medici was murdered by his cousin and would-be successor, Lorenzino dei Medici. Lorenzino's treachery forced him into exile, however, and the Florentine senate accepted a compromise candidate, seventeen-year-old Cosimo dei Medici. The senate hoped Cosimo would act as figurehead, leaving the senate to manage political affairs. But Cosimo never acted as a puppet. Instead, by the time of his death in 1574, he...