Francesco de' Medici, second grand duke (granduca) of Tuscany, had been appointed head of government in 1564 while his father, Cosimo I, was still alive; and he had succeeded his father as grand duke in 1574.

The title is not precisely legitimate since it had been bestowed only on Cosimo by the pope in 1569, but Francis had obtained the grand ducal title from the emperor Maximilian II in November 1575.

By subservience to the Habsburgs, he has won recognition of his dynasty's hereditary right to all his possessions in Tuscany; and he had refused an invitation in 1575 to stand as a candidate for the Polish crown.

He sponsors Bernardo Buontalenti's plan for developing Livorno in 1577, which is to make it the greatest Tuscan port; he strengthens the fleet; and he opens several trading posts in the eastern Mediterranean.

A scholar and a keen student of chemistry, mechanics, and ballistics, Francis also continues his family's patronage of artists (notably Giovanni da Bologna) and is the first to house the Medici collection of paintings in the Uffizi Palace in Florence.

His reign is tarnished, however, by domestic scandals: his brother Pietro murders his own wife, the younger Eleanora de Toledo, on the night of July 9–10, 1576; his sister Isabella is murdered by her husband Paolo Giordano Orsini, duca di Bracciano on July 10 of the same year; and Francesco himself will largely live on in the romantic popular memory because of his love affair with Bianca Cappello.

Bianca, a Venetian noblewoman renowned for her beauty and intelligence, had run off against the will of her family and married a young Florentine named Pietro Buonaventuri.

She had soon become the mistress of Francesco while he was still heir presumptive, at first secretly and then openly after the murder of her husband in 1569.

Nothing could ever deflect Francis from this passion—neither the marriage with Joanna of Austria, nor the reproaches of his family and of the Emperor, nor public censure.

When Joanna dies in 1578, after giving him three children, Bianca succeeds in marrying Francesco in 1578 by means of a bizarre plot in which she feigns a pregnancy and presents him with the baby of a common woman as her own son.

Francesco has her solemnly crowned in the Palazzo Vecchio.