Why was Alessandro de’ Medici made hereditary duke of Florence?

Alessandro de’ Medici was made the hereditary duke of Florence primarily to ensure the continued rule of the Medici family in the city. By the 1520s, the direct descendants of Cosimo the Elder had become few in number, prompting Pope Clement VII—who was himself a member of the family—to secure the succession by installing Alessandro as the hereditary leader.1

This transition was formalized in April 1532, when a new constitution was enacted that abolished the old Florentine republic and declared Alessandro the hereditary duke and perpetual gonfalonier. This move was supported by the Holy Roman emperor Charles V, who had previously agreed to restore the Medici to power following the siege of Florence (1529–1530) and had nominated Alessandro as head of state in 1530.21